I don't have your make fifth wheel, but you should have a circuit breaker/fuse box that looks similar to the one in the picture below. It's the brown looking box under the fridge. Open it and you will find the fuses and breakers. Yours may not be by the fridge but it will probably be somewhere close to the floor.
If your GFI outlet needs to be reset, it will look like the one in the pic below. It will probably be located in a bathroom or wash bowl. Press the reset button.