I don't mean to hijack the thread, but hopefully the OP will agree that keeping warm in the off seasons might be germane to the discussion.
Feel free to hijack! As more people contribute to this thread, more knowledge gets shared.
Here are the results from my latest field test with the Propex:
1) After setting up my tent and the heater, I discovered the valve on the propane tank was broken. I tried every possible socket and wrench to open it, and only succeeded in stripping it. Fortunately, I was able to travel on foot and obtain another tank. There's a lesson in this story somewhere . . .
2) I wrapped the exhaust conduit around the propane tank, thinking it would make a small improvement to the tank temperature, helping to keep it from getting sluggish and lowering the pressure. I learned that the exhaust causes a LOT of condensation, which leaks out of the conduit and freezes into ice. When I disconnected the conduit at the end of the trip, there was a lot of water trapped in the coils. I'm not sure it's worth trying to find a different solution, since the conduit does work very well for routing the exhaust away from the tent. You can see the exhaust pumping onto the hood of my Jeep in one of the photos below.
3) I tried the 3-candle UCO lantern, which is rated for 5,000 BTUs. I guess it warmed up the tent a little bit, but it seemed most of that heat pooled at the roof. The propex system, however, cycled wonderful, dry warm air into the tent all night and kept it at 65F. It was very impressive how well it worked. Depending on where we set the thermostat, it was probably on five minutes and then off for 15 minutes, all night long.
4) Finally, I included a photo of one of the air vent soffits that is at the top of my tent. I noticed the seams are sealed to prevent leaks. For some reason, I've never noticed that detail before. I wanted to show the picture here as an endorsement for Tepui tents - I have been very impressed with my Autana Sky tent!