what says reverse polarity
one of those little tester plugs ?
i got one , it says open ground, every time i run the portable generator
those things, are not for testing generator power
which does not have an earth ground bonded to the neutral wire
AC does not have a real polarity, just an assumed polarity to make sure bonded neutral is always in the same slot, always on the white wire,
if everything works, just run it
if your power management system panel inside the RV says reverse
then use the bonding plug described above