Use the 50A adapter - can't hurt a thing. I agree with what most are saying, issue is with the outlet, not your unit. If you want to be sure, unplug and start the generator. If you're pulling too many amps, the gen won't handle it either. I know for a fact you can run a 30A MH, with everything on except the microwave (water heater on propane) on a 15A household circuit - did it for three years in my drive before I put in a dedicated outlet. And that was using a 50' extension cord. Breakers can get "weak" and become easy to trip with age. Hopefully, the 50A breaker will have seen less use over the years. Good luck!
2015 Legacy SR340 360RB
2014 Jeep Wrangler Unlimited Toad
Gigi, Poppy and Sadie Lady...On the road, but not full time!