Goldcoop
I have several serious sleeping bags that work well. I have a North Face Mummy bag rated for -20 and I melt in it unless its below freezing (I bought it for a climbing trip out west) and I have several other 20 degree bags that are perfect for me in most winter outing. But it's a camper and I'm looking for cumfort. Also being a newly married young couple ...... well the sleeping bags just don't work.
I like the latern idea very simple. I have a candel lantern that I us in the tent all the time and it makes a huge differnce in the temp.
As far as turning the radiant floor or water radiator into a a/c unit it would work but not here in the southeast. If the air is not dried then the humidity will kill you.