Outdoor mouse tank?

Hi, So I just set up a 1.4 mouse colony. They're living in a 10gal (30gal in a couple days, once I dig it up) tank. I suppose I might split the tank into two colonies once I get some births.

Anyway, They're living in the garage because they smell way too bad to have in the house. The garage isn't heated.

I picked up some RV tank heater pad deals (something like flexawatt). I was thinking If I'd stick that on the bottom of the tank and rig a thermostat, and maybe a lamp or two on top, they'd be ok in the winter?
I thought I should probably add styrofoam on most sides too, I guess.

It's been known to get down to -40 or worse here, but the garage is usually somewhat better (being semi-detached, insulated).

I guess I'm just looking for input, if anyone has a similar setup.

I keep all of my rodents in my un heated garage. I am in New Jersey so the temps NEVER get as cold as yours...but when it gets down to 0 or so, the garage stays around 50 or so. The body heat of all the rats and mice help keep temps up.

Mice alone would need some heat. They are too small to be able to withstand those cold temps. A space heater maybe??

I would think that a heat lamp AND UTH would be way overkill. But if your garage does drop to freezing, they might need a little heat output(especially if it's only a couple mice in one container, rather than several). Insulating whatever they are in would help a lot also. Since a UTH would require a thermostat, I think I'd just go with a lamp with a small bulb, insulating the cage with styrofoam to keep the temps in. You'd have to cover the top a little too, to prevent all your heat escaping.

Of course, I'm in Florida.... we don't get -40 unless we go into a deep freezer.