Finish growing in the garage or leave them? It's getting cold and windy at night.

I have 2 beauties that are about 3-4ft tall, both were topped and have a good amount of top buds. Hoping to get about 4 oz's off them, dont know actually since this is my first outdoor grow. No idea how big the buds will get with the fertz.
Im very worried I will have some frost effect to my plants soon because in my area frosts are known to come early.

Do you guys think it would be a good idea to put them in my garage to finish them under 2 of my 500 watt/hps heat lights ill be bracing on the beams of the top of the garage facing down on angles on both plants and a 10000 luminecent bar light ill be hanging in the middle.

This would be the design:

..v.light............light.v..

l./.....l................l.....\.l
l.......l................l.......l
l.......l................l.......l
l... _______________...l -- <- flourecent
l...............................l
l ............................. l
l. ......u.......... u........ l <- Plants
-----------------------

I'll have it timed with a timer on 12/12 for budding, and still feed them their bloom fertilizers. At least in the garage I can completely finish the plants. I'm going to be insulating the garage a bit more before i put them in to ensure the garage stays at a decent tempature.

But would this be my best bet to save them or should I leave them outdoors and let nature take its course?

Well the plants are in there now. first day; does anybody want to fricken help out with the setup? I meean some of the buds have shade on the sides. whats a good way to make it so everywhere gets light.