Why not get everything ready to paint in the garage or where ever. Turn on your heater for a day or so, every thing will warm up and then turn it all off while painting. Unless your going to take all day to paint it should be fine. I heat my shop with LP forced air and do just that. I run a air line from the other shop so my A/C won't come on while I'm painting. After the fumes have cleared you can rewarm every thing.