I've used the coleman blackcap heater before. While camping out for Black Friday shopping. I was in a 3 season, 3 person tent. and it was 5 degrees outside. We vented the top of the tent pretty substantially, as well as the bottom of the fly. and 3 of us were inside the tent, in shorts and tshirts...I realize its not quite what your thinking. But it was very efficient and effective.
Also, i'm not thinking an alcohol heater would be very effect at all... It would take a lot of fuel to produce very much heat. However, i did find this, I have no idea how well it works, and you would still need to figure out a way to vent the fumes effectively. http://www.smallspacesappliances.com/alcoholheaters.aspx
I know you didn't like the idea of wood, but maybe you could turn this into and alcohol heater somehow...