Years ago, I had a 'i83 Southwind with a 454 in it. As I recall, the shop manual stressed the routing of the ignition wires because of possible cross firing between cylinders when an wire for a firieing cylinder was routed next to a cylinder on a intake stroke.
Mine used to "sneeze" wnen under full throttle oe heavy load. As the pressure in a cylinder goes up, the voltage required to spark across the plug gap goes up, making the likelihood of a sneak path firing occur, when that sneak path goes to a cylinder in the intake cycle, you have a combustible mix, an open intake valve and you get a backfire through the intake manifold.
Besides the ignition interlocks for the slides, you probably have interlocks on the basement doors to prevent damage. Those doors have to be closed on my coach for the slides to operate.
For limited power, get a 50 amp to 110 volt adapter. That gives you 15 amps that will operate the charger. It will also operate the refrigerator or the water heater for getting ready for a trip, or for cleanup. 110 volt extension cords are cheap and available in 100 foot lengths.
Dick Lucas, '04 HR Imperial
On my '97 holiday rambler endeavor I was able to track down the source if my wind noise by moving a small pillow around the window until the noise stopped. It turned out that the weep hole cover closest to the front was missing. Black tape was my fix.
This may not be your problem, but it might help you to locate your noise source.