for super efficient heating option just a little less hp than the buddy heaters and even less likely to co2 scare you try the Olympia Wave 3000, get the little angled feet, a 20 lb bottle will run it a long long time. It has 2 settings, 1600 btu and 3000 btw...the buddy junior runs 4000-9000 btu but it uses a pilot flame which is far less efficient, they put out great heat but burn up propane, the Olympia Waves are 99.98% efficient, I've used both ice fishing and otherwise in smaller cargo trailer build, I had 2 initially but ice fishing so much fun I installed a diesel heater in trailer but still keep one wave 3000 on wall with a grate above it for keeping water warm for thawing ice in holes and it's fantastic for warming up meals but at 1600 btu on low would be an ideal tent overnight setting, crank to high when you get up, keep a couple vents open and you're all set, the wave 3000 I'm thinking more for the hot tents sizes, cimarrons etc. and I will run one in mine when truck camping from tent, for larger wall tents you'll need way more btu's
coghlans makes a small campfire grill about 6" wide that's super cheap and in every sporting goods section that modify to easily slap on top of a buddy heater or the wave...the buddy junior can percolate coffee in a 6 cup, those little buggers get super hot, you will only warm food over time on the lower outputs of the wave 3000
Olympia wave's aren't cheap, but this forum has super fat wallets so good place to mention them

, they are used in lots of rv applications and longer running more permanent installations but they are the most efficient things out there for propane heating and will give the most output with least co2 produced and lpg consumed, the van lifer crowd put me onto these. Dry heat is better but wet heat is better than no heat. They have bigger models also, 6000+ btu but the little 3000 is pretty versatile little set up for smaller tents/cargo trailer/van size spaces.