New Member - Have Pregnant Stray

Hi, my name is Rebecca and I am a new member who has aquired a pregnant stray. She is a sweet little tabby who showed up on my porch (we live in the country where losers dump their animals when they don't want to take care of them). She was very skinny except for her obvious tummy bump and she has put on a bit of healthy weight just since I started feeding her 5 days ago. I took her to my vet and her FLV/FIV tests were negative - thank goodness - but he couldn't tell me for sure how far along she is. I have decided to keep her at least until she has the kittens, then spay her, give everyone their shots, and try to find homes for all of them. I have 2 large dogs and 2 primarily inside housecats (both spayed/neutered). I am afraid my male cat might pick on her and the kittens since he can be a stinker to my female cat sometimes. My husband absolutely refuses to have any more animals in the house anyway, and our house doesn't have a room conducive to being shut off to raise kitties for a few months anyway. I have taken in/found homes for many strays over the years, but can only keep so many at once. I am a total stray magnet - they even find me on vacation. I brought one of our dogs 900 miles cross country after I found her dumped near my parents' house and couldn't find her a home during my week there. Hubby doesn't mind spending the money for vet care/food/etc., but just no more in the house - so.... we have fixed up a rather large unused dog house that is located in a fenced in garden area. I brought in bales of straw for insulation and made it as draft proof as possible and added a comfy bed. It is dry inside during rain, as well. I guess my big concern is that when she has the kittens in the next couple of weeks (we think maybe 2 weeks) it may be in the 40s at night outside. It stays much warmer than that in the "cat house" but I worry about newborns since I keep reading that I need to keep the temperatures higher for them. Will the mom's body heat be enough to keep them warm or do I need to take additional measures? Any suggestions or advice?

Unfortunately, our house is small with a fairly open floor plan. We have bedrooms for us and the kids and a couple of small bathrooms that get heavy use. Our laundry room is the only way into the house from the garage, which only has one entrance and also gets heavy use. We have no basement. I know, our floorplan and design stink, but we weren't the ones who built it. In short, no place to isolate or confine her. Even our closets are small and jam packed. That said, she seems to be fairly safe and content in my garden "cat house". She is fenced off from the dogs and any predators and doesn't seem inclined to go elsewhere. I really wish I could bring her in, but I honestly think the danger to her from my dogs and wild-man male cat would be worse. I plan on gradually socializing her and the eventual kittens with the dogs and other cats, and thus, bringing them inside for short periods of time under close supervision after the kittens are old enough to do so. I was just wondering if outside cats usually do ok with keeping their kittens warm if they have shelter. Has anyone ever used one of those electric kennel mats? I could probably safely run an outside extension cord out there to operate one, but a space heater wouldn't be safe with all the wood and straw.