I doubt that the owner would remove the GFCI as it may be a code thing or his insurance company probably requires it but to plug an RV into is asking for false tripping. 30 and 50 Amp outlets at home or a campground are not usually GFCI protected.
Googled this info...........
GFCI breakers are designed to cut the power in the blink of an eye if electrical fluctuations of as little as .005 amperes are detected. Because the GFCI is so sensitive, it is most effective when wired to protect a single location. The more outlets any one GFCI protects, the more susceptible it is to phantom tripping – shutting off power because of tiny, but normal fluctuations in current flow.
GFCI breakers can also be tripped by occurrences such as electrical storms and by moisture from rainfall. It is important that the outlets for the GFCI be kept dry and protected from the elements. Most GFCI’s rated for outdoor use come with a protective cover.
Some GFCI’s are more sensitive that others.
t may be that the GFCI is too sensitive. It is normal for continuous running motors, such as pumps, to sometimes have small electrical fluctuations. Sensitive GFCI’s may detect this and falsely trip.
Good Luck with what you find.
Are you using good cords & a dog bone adapter. Check your adapter set up to make sure all is good. I know you are using a surge protector.