RMH + wall tent?

Could a rocket mass heater make living in a canvas wall tent long-term in a cold climate viable without needing to clear out acres of forest every year and spending half your waking hours splitting wood?

If you have to live in a wall tent thru the winter (Who would want to though) then Yes, a rmh would use less wood than anything else available.  You would spend a good portion of your day splitting and loading wood.
 But hey your living in a tent outside in the middle of winter... you got to do something with your day.

I've stayed in them before (short-term) in cold weather and think they're super cozy. Wouldn't mind using one as a tiny house with the addition of a composting outhouse and a sauna for washing up in. They just use an awful lot of wood and I wondered how much a rmh would bring it down.

Wheaton Labs has a Tipi with a rocket mass heater:  

Awesome, thanks for the link man. Do you think a teepee is inherently more efficient than a wall tent? A yurt is about the same shape, maybe the reason has something to do with heat? Then again, maybe not. I'm talking canvas here, not made out of beaver or yak pelts or anything haha.

The magic here, apart from the virtues of a mass heater, is surface area.
A wall tent is more or less like a box, yes? A tipi has a round floor plan and is shaped like a cone, a yurt is lower and circular with a typical slightly rounded roof. Both those shapes have a much better volume to surface ratio, making the heat losses lower. For example: a cube with a flat roof of say, 10' x 10' x 5' = 500 cu.ft. of volume. The surface area of that same tent is 300 sq.ft.

A yurt of the same volume, assuming it's just a cylinder with the same height of the cube, would be nearly 11.3' in diameter. The surface area of that yurt would be 277 sq.ft. , including a flat roof. Better, but not much.

A tipi is cone shaped of the same random volume again. Let's assume the tipi is 10' high, so the floor diameter would be about 11.3', same as the yurt. The point here is, the tipi consists of wall only, no flat roof. So the surface area of the cone shape is diameter*pi*height/2 and in numbers 11.3*3.14*10/2 = 177.5 sq.ft.. Which is waaay more efficient as compared to the wall tent in terms of volume to surface ratio, unless I made a mistake somewhere in the calculation.

The yurt has more usable floor area, the tipi is much better optimized for heat loss. The wall tent is the least efficient of all three.