The problem with that type of fireplace is that it draws cold air into the tent to supply the air for the fire. That keeps the smoke out, but makes for a very drafty room. I don't think you'd really warm that tent much with that set up, but I'm sure you could feel some heat coming from it.

I never seen a poncho rigged like that though, that's pretty cool. I think a tent like that made with the SOL emergency blanket material and a bubble foil floor would be a pretty good UL set-up for those into minimalist backpacking and could work great with a candle heater.