Unless you are going to carry a 6' copper rod and drive it into the ground at every stop, there is no realistic solution to ground generators (built in ones have the same issue).
Realistically, unless you have a real rats nest of messed up wiring, it's a non-issue.
In simple terms, the ground completes the circuit back to the power station. Since your RV cord has a ground wire that links back to the power station (your generator), it's covered.
I work with electritians regularly. Grounding and bonding is a messy subject. Ask 3 electritians the correct method to ground and you will get 6 answers that disagree.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV