My fifth wheel trailer has a GFI breaker in the bath room area and the kitchen sink area. The one for the kitchen sink also controls the outside 120VAC receptacle...
Since a lot of your 120V appliances and items are working it sure sounds like a GFI Breaker is tripped somewhere...
The GFU breakers of course are pretty easy to spot as they have a RED button in the center of it...
The 120VAC Breakers in your 120VAC Power distribution panel sometimes don't look like they have been tripped. as referenced by another post here. You may want to look again at those and perhaps just turn them off one at a time and then back on...
My 120VAC Power Distribution panel has one large size 30AMP Master Breaker and then eight half physical size breakers in the remaining four breaker slots.
Another issue that only the slide-outs have is that they will have a flexible cable supplying the 120VAC to the slide area. It could be possible this flex cable has been damaged...
Roy Ken