Glen, if you're going to have two traps, that's what you have to work with! There are a lot of trapping hints/suggestions in this thread: Helping Ferals: Socialization, Trapping, etc.
We've never had to trap cats that weren't near us. We would put out the traps and pop outside every 15 min - 1/2 hour or so. We did trap the same cats several times, and we would just simply start over again.
Best thing, I think, is put out the traps with food in them. I doubt you'll get more than one cat into a trap - but you never know. If two walk in there (two would have fit into the traps we used) - I guess so much the better?
But best to put out the traps, put the food in there, and get out of sight as much as possible.
I guess you could try putting out boxes first and feeding them in there. Might help get them used to "going into something" to eat. If you put out four boxes with separate food bowls in them, maybe you'll get them used to eating separately inside of something?
And definitely have them ear-tipped, or have a notch or something done as a sign to both you and others that they've been fixed. You may want to start a "TNR journal" and keep track of the descriptions of the cats you've had done, dates, etc...
Trapping the first two might be easier than trapping the others... BUT - if you get them used to going into boxes to eat, you might even be able to use crates to trap them! We were able to do that with a couple of them. Just feed them in the crates and then shut the door. With ferals that won't work unless they're used to it, and you might not be able to get them to go in there to eat, period. If you do, you have to be VERY quick about it as they're fast!
The trapping hints should help for trapping the others if the first two are fairly easy.
And for really hard to trap cats... if they're used to being fed every day, if you skip one day, it might help. It helped us. But I wouldn't skip more than one day. You don't want the cats to think there's no more food coming and stop coming by at their regular time...
When you go to release them, what we always did was put wet food out before opening the crate. Some of the more "comfortable" ferals would eat it before taking off... others just bolted. But it helps them know it's still a "friendly" place where they're going to get fed.
Again - if MA (hissy) has any tips here, I'd take them!!!!!!
Good luck, and I really hope you keep us posted!!!!!!!