Thank you both for the response! I have the bus it is a 2001 33' transit style with a 5.9. The plan is to travel around the Americas.
My idea for the mass was to do gravel or some other kind of rock in a frame. I'm thinking something like hardware cloth in a welded 1" angle iron frame or possibly a lumber frame. I should be able to mitigate the weight by putting it over the rear axle with the water tanks on the opposite side. I have seen people turn these into toy haulers and carry big lifted rock crawlers on them so the weight should be ok. It's the core material and chimney placement that I'm not sure about.
It seems like a metal core would hold up to the vibrations and flexing better but from what I've seen they don't hold up to the heat and burn out fairly quickly. But a good insulated core like I see in Paul's videos doesn't seem like it would hold up to the movement.
Obviously I wouldn't be burning while the bus is moving but I don't know if running the chimney up through the roof would work. I don't know what the air path through the roof would do while moving. But I guess I could build a way to close it while moving.
33' with a 5.9, is that a class A, with a pusher ?
Sounds like its big enough to handle the weight.
As far as the chimney. Thru the roof is best. Not very high up at all. Support it with cable for wind resistance. I would think a cover strapped or bolted on while traveling would stop drafting from the stove.
A brick and clay core would crack on you with travel.
A possible option could be, to use ceramic fiber boards for your core & a ceramic fiber 5 minute riser. Both would be vibration resistant.
Refractory concrete would be needed in place of fireclay.
A brick bell could be constructed, using the refractory. Keep the shape square and utilize steel straps and all thread to "lock" your brick bell together. Possibly down to the floor itself.
Check out this recent thread for what looks like a cool little self-contained RMH all in a single barrel. I think this would hold up to the stress of driving around, and it's an appropriate size for a bus.
Personally, I would go for Uncle Mud's Cottage Rocket. The Poelito is technically not that good, the Minnie Mouse is a bit complicated to build and get air tight.
The Cottage Rocket on the other hand is spot on for simplicity of build and from a combustion viewpoint as well. OK, it isn't easy in case you've got two left hands with all thumbs, but a reasonable handyman could build it just like that.
Wow, I had completely missed the Cottage Rocket! That does look a lot more robust than the Poelito, which has a flaw that I don't like for indoor applications: There is incoming air across the ash grate which would very easily start burning the sticks up the feed tube and smoke you out in no time.
As someone experienced with Towing you're going to want to Center your weight between the axles as well as balance the load from left to right ideally you would put it in the middle or you could put it off to one side with some type of counterweight on the other side
No matter how you go about this your mass is going to be considerably smaller you should also take into account the weight of at least some wood But a bus is not the most ideal thing to use as you're essentially in a big soda can and aside from having a small heated bench for the comfort of sitting on it's not going to keep said soda can warm very long
Not saying it's impossible just not the most ideal vehicle for the job I've always been partial towards enclosed utility trailers or travel trailers possibly fifth wheels I always thought an RV with its own motor it's kind of is short-sighted way to live on the road for a number of reasons
There is a tiny house out there with a pizza oven. Not a RMH, but that's the closest thing I've seen. I doubt they move their house around a lot, though...and it sounds like you want something very moveable. Here is an article about the tiny home: Euro-style Tiny House with Pizza Oven
Be joyful, though you have considered all the facts. ~Wendell Berry