There have been posts here that GFIs should not be used on bus systems?
I don't remember the reasons but some of our elect experts surely will chime in.
Not an elect expert (by ANY means) but you may be thinking of the fact that a GFI will often not work as a shore plug socket. Has to do with the switched grounds etc. on a bus with an automatic transfer switch, I think. I know that my bus trips a 20 Amp GFI but I think that my 15 Amp adaptor (which goes to a 30 Amp adaptor which goes to the 50 Amp plug) only supplies power to one leg of my 50 Amp service anyway. One of those "it works pretty much right and I'll take care of important things that don't work and then get around to finding out WITH is wrong with it" things, I guess.
As long as I'm not tripping a GFI in the garage wall, the GFI next to the bathroom sink in the bus seems to work just fine.
BH NC USA