The one RV appliance that requires no more LP than a residential version is the RV range. When you take a fuel with a certain BTU and burn it completely you get a consistent heat output. RV ranges direct the flame towards the bottom of the pot or pan, same as residential ones. As for the oven, it's possible that an RV one may have less insulation, but the old Master Chef I installed does better at staying cool on the exterior than the residential one I frequently use. It can cook a mean shepherds pie, as well
Cheap and flimsy? Oh hell no... This thing is a brick. The only plastic parts are the dials. Now, take the natural gas stove in my last apartment: it was almost the same weight as this little stove, though it was full-size (good or bad?), had plastic everywhere and a thin gauge top. It rattled when you shook the floor around it (kitchen dance parties). It would've made a racket going down a bumpy road.
Interestingly, the oven gas elements look about the same in both ovens.
I'm no baker so can't say anything about how evenly the RV ovens bake, though.
What I'm saying is that there's crap in both worlds. If you want to save space, go with an older, solid RV/boat propane range.
In the days before living on a rubber foundation we found ourselves cooking in the toaster-oven far more frequently than the oven. If you're like us then you'll do just fine with an RV oven.
Now, RV furnaces are another story. I've yet to see an RV furnace that I'd consider using. Furnaces are different heating devices than ranges because you're trying to keep the exhaust outside and get the heat inside. This requires a heat exchange. The RV furnaces I've seen have way too simplistic heat exchanges with too little surface area. Outside the exhaust is HOT, meaning it isn't efficiently transferring heat.
I bought an Eccotemp L5
to use as an on-demand water heater. It functions well, but has the same problem as mentioned about the RV furnaces. It's probably only 50% efficient. The other 50% of the heat billows out the top. I'm building a forced exhaust system with an additional heat exchange to try to pull more of that heat out of the exhaust..