I'm not much of an electrician but I'd disconnect the wiring to all appliances and then individually run a wire with an inline fuse directly from a 12v source to the appliance. If they run fine, you know for sure there is a short in the RV line somewhere. A puncture from a nail or staple would be my first thought.
2020 2205S Rockwood Minilite
2019 F 150 Lariat 3.5 Eco Fx4 Max Tow
Equalizer WDH, 1809 lb payload