I was gunna try an do something like this in my trailer, this is a good idea, I would also get a little work bench in there if you can, I have had to many times were I need a little work bench for a motor swap or something along those lines. As far as heat, put insulation in it and use a small generator and small electric heater, that's what we have done for the past couple years but been sleeping on blow up beds. Post some pictures up when you do some stuff, I always like looking at other guys setups.