Prove that it's not fuel related. You obviously need to be careful when doing this but I would try to richen the mixture just before you close the breaker. I would locate the air filter intake and use a propane torch to feed it extra fuel. WITH THE TORCH NOT LIT
Don't come back with your eyebrows and hair singed and scream at me if you mess up at this. You want to feed it a little extra fuel so as to prove that it's not dieing from a lean mixture. First just have the gen running and put the torch tip near the air intake so you will be feeding it extra raw propane. As it richens the air fuel ratio it will start to blubber or run rough.
Experiment and find what causes it to go rich without massively effecting it. When you have it running richer flip the breaker on and see if it dies out. If it doesnt die, you have fuel/intake/regulator issues. If it still dies it is more likely to be electrical.
At that point I would want to run the gen NOT connected to the camper. Power something else within its rated wattage to see if any load kills it or the camper kills it.
