Multiple positions on this.. but here is mine.
Though the CODE for wiring says "Neutral and ground are bonded at the service entrance" (Main distribution box) if you go to most any RV park you will find that often each box has its very own ground rod. So grounding at the site is ... Not going to cause problems.
Drilling through a brick wall is also very easy.. I have a hammer drill and masonry bits They go through a brick wall like it was soft Pine.
Now we get to the tricky part.... In the parks where I notice each box has a ground it's a single ground rod.. Code now days is 2 ground rods. with a minimum distance between them, 10 foot.. I won't advise that is the term "overkill" applies. but Well....
YOu do have options.
Finally, the ground is a safety, ideally it never does anyhting but sit there.. In practice, you may find the "Skin" of your RV hanging in there at around 60 volts, amost no current ability (60 very high impedance volts) but still 60 volts without a ground.
I can also ground the RV chassis on my rig if needed (Do it boondocking for other reasons).
