$250....yikes! I have a friend currently rigging his tent with a light weight stove. Basically a sled dog type rig, easily packable, well vented. It's not ultralight by any means but I'm wondering that if a warm tent is the goal, bringing the fire inside isn't the best way. As a Boy Scout, we made tent heaters from a soup can, some cardboard, and paraffin, which did the trick beautifully. The problem I've always had with campfires/tarps is wind change. And around here, it changes every 10 minutes.