How can I lessen his separation anxiety, or at least cushion it?

Lux never used to be very troubled by my or my live-in partner's absence, but recently we all have bonded more and he seems to feel much closer with us - seeks us out more, even cuddles. 

At the same time my partner and I are doing a work thing together that requires is to be away for 3 days a week every week for 2 months, and on top of that we're taking a week long trip in June.

The first time we had our three days away recently, we came back to a Lux who seemed stressed and excessively snuggly. I could just tell he was frazzled. Not to mention he scratched a bald spot on his ear (he might still have a couple of fleas but he has never scratched that badly before even with terrible fleas). 

I can't afford automated toys for now - I know I'll be getting one for him once finances pick up, but right now I have to choose between that and feeding him his usual premium food, so the choice is clear. And we are getting a kitten but that will be after our work thing is over.

If anyone has a suggestion for how to make time alone easier on this incredibly sweet cat, I would love to hear it. He already has severe anxiety issues (something like the kitty equivalent of generalized anxiety and OCD) that are getting better slowly but surely, and I'm worried that this major stressor will result in a worsening of his anxiety. 

Invest in some Feliway diffusers and run those 24/7.  Also, be sure you have someone checking in on him twice a day or stay overnight if possible (combo house sitter/cat sitter).  Be sure to leave dirty (as in worn for a few days) shirts around in various places he sleeps so he can smell your scent and be comforted by it. 

When you say 3 days away do you mean 3 days including over nights, or away during the day and back for the night time?   

@Stephanietx: Thank you! I did not think of the Feliway. Unfortunately that's another thing I can't afford right now, but that's going on my priority "buy-next" list. I will do the T-shirt thing though. I'm not able to have someone visit except on the week long trip.

@MServant  It's overnight.  

3 days plus nights alone is a long time for any cat to be without company.  Also for making sure safe supplies of food and water are kept up.  Is there no one who can call in for you even if it is for a short time?  Perhaps go in to check things are OK, turn a TV or DVD on for a bit and go back to turn off later?

@MServant: There's really not anybody I can ask to check in on him. I usually get my landlord to but she has been going through a tough time with family issues and is too busy, and she also wouldn't allow random people to be allowed into the house. I have a kitty water fountain so the water issue is taken care of, and I leave out enough food for the three days. Maybe I'll get a radio or something and leave it on for him during those days. I have read before that this helps with separation anxiety in kitties.

If you try the t shirt scent thing, plus maybe radio so there are some human voices Lux can choose to listen to it might help some.  

The other thing to think about is using the technique suggested with dogs if you haven't done this already:  where you go out for a short time ( like a few hours ) and then fuss, attention and treats when you come home.  If he gets more settled and secure with short separation then gradually increase the time.  It will be difficult to get anywhere near your leaving him for three days but it may help Lux learn that you can go away and come back.  I think it really helped Mouse when I was working full time and long days of up to 10 hours.  Initially he was very clingy when I came home but once we went through building up the time he seemed to understand what was happening a bit better and that he would be waiting for lots of play and cuddles and treats when I came back in rather than hiding underneath me and frantically trying to share our scents.  If Lux is reluctant to come close to you and is very wary when you come back in perhaps changing your clothing back to things which smell of your home and of him will help too.

I hope you manage to reduce his anxiety a little.

Imagine being deserted by your family for 3 days and not knowing when or if they'll come back.  Most likely, the kitty is going into some kind of depression and anxiety over realizing he's been left behind.  I would call your vet's office and ask them if they know of any reputable pet sitters.  If you don't want to do that, then board him at your vet's office just so he won't be left alone.  Three days is too long to leave a pet unattended.

I feel your pain! Seperation anxiety is tough on both the pet and owner.
When you can, I recommend the calming hormone diffusers or collars. (FELIWAY works best for me and the cat so far). I know the collars are much cheaper, and so far that's what I use. I only put it on him when it's a long work day or a rare overnight alone as I've noticed daily wear seems to decrease collar strength (i.e. it stops working for him, even with fresh collars, I believe it's because he wiggles them off over time an licks the scent off by 72hrs >.>)
I would recommend cat sitter or if he is very stressed and mutilates, maybe a cat hotel? Unfortunately, I understand cat hotels (or a good sitter) takes a lot of trust and money.
we also live where we don't have a friend who can help out since we moved states.

Some other tricks that showed some improvement or I've heard of (let me know if any of it works!)
1. Buy or build cat furniture! Even if it's unsightly or in the way, a cheap (but safe!) environment helps! YouTube has how to videos, and I've seen things such as a cat tunnel and a big delivery box that created a little hide and play one story structure, 2X4s and some sisel rope makes a quick and inexpensive scratch post and/a perch, etc
2. TV, Radio, DVDs, Videos, etc (youtube connects to my phone via Xbox, so I stream him videos and they're free)
3. Don't wash the sheets right before and/or place worn clothing in/near favorite spots to help them feel your around
4. GOOD LITTER
5. Leave blinds open (or at least cracked enough they can see out?). I leave windows cracked for fresh air when I run errands, but that may not be an option when gone overnight.
6. Buy or make toys (youtube to the rescue!) put of of the favorites away where he can't see/play with them and only put them out when you are leaving. Make sure to rotate them to keep it more interesting.
7. Lots of play while your home
8. Puzzle feeders, or puzzle treat dispensers. Again easy to construct basic ones, though my kitty needed to be shown how to play with them before he got it. Puzzle feeders are great but they recommend you either don't leave them alone with just that for too long (keep another source handy) and that the cat "gets it" before you leave
9. Medication if cat hurt self, screams excessively, doesn't eat, and other health risking behavior
10. Get a companion (but make sure they're VERY adjusted before they are left alone overnight.)
11. Get a non-cat friend, such as fish (with cat proof bowl but viewable), snake, frog, dwarf breed rats/mice/hamsters... Pretty much anything easy to care for, prey like, low intellect enough not to always be afraid, and in a cage that can be cat proofed by still viewable.
12. Bird/squirrel feeders, and now they have transparent bird feeders/houses. (I want to try this)
13. Auto food feeders. Sounds weird but it's already helped my cat. I think for him the comfort of knowing the exact feeding time, and the link of me = food is broken, so he has faith he will eat if I'm not home.

Mostly my vet said it's not just the anxiety of "losing" me in the cat sense, but often boredom that causes stress behaviors, as the cat relies on it's human for not just comfort; but stimulus, play, and food.