I guess it depends on the camper. We have a Winnebago, and the canners I have just would not work on that stove. Not enough room. Not to mention what the inside humidity would do the the rest of the space. Peel the wallpaper, maybe
Outside is better, I think.
OTOH, we've lived in our motorhome for months at a time, on the road, and I used the stove and oven all the time for cooking our meals. And the heater that came with the unit. nb
Now, I have recently been doing a lot of canning on our household stove.
Actually, it is two apartment size stoves, very simple, with no electric elements, side by side. So I have eight burners, and can run two pressure canners, or two water bath canners, with the attendent hot water supply, to top off the canners if necessary, and, of course, the product to be canned being kept hot in a double boiler rig. When I pressure can, I can preheat the jars in the water bath canner, and preheat the product, so I am "really" canning hot pack.
Do you see why I said the standard RV rig would be 'way too small?
Now, when we were shopping around to buy these stoves, we checked out a commercial stove. We were immediately told how much energy these things drew down, and it was far over what a standard domestic gas stove draws.
You do not want a commercial stove. A mediocre gas stove will do. If it has lots of burners and is in a non drafty spot, and you have lots of counterspace and two or three sinks in your kitchen, all the better.
Before we started canning this season, I had the propane tank filled, and I took careful note of the gauge. After each canning session, as above, I go out and look at the dial. It moves very little! Maybe a point. So a 200 galloon tank, filled to 80%...and the dial moves one point per each canning session.....
You do the math....my brain has gone to bed already~