[JRTJH]

Any ground, whether on an RV, a drill (the old 3 wire/3 prong metal case tools) or any other device that's "grounded" is only as safe as the highest resistance on the ground circuit.

For instance, if the ground is actually 10 ohms (it should be 0 ohms) and you're standing in water (making YOUR ground circuit "less than 10 ohms" then any electrical charge will seek the "path of least resistance" and you'll become the ground.

There are a lot of "ifs" and "ands" and "excepts" in RV electrical circuits. Your assumption that the RV chassis is grounded and the skin is grounded to the chassis, "SHOULD" mean that the skin can't become hot.... That is: IF the ground circuit from the RV, through the shore power cord, to the campground pedestal, then through the campground wiring back to the campground "ground stake" is less resistance than "you and your wet feet" as you touch the trailer skin..... That's why the trailer neutral and the trailer ground are separate and not bonded together.

Typically, it's not a problem, but with a direct short from the trailer wiring to the trailer ground, there's no "guarantee that the campground "ground circuit" is going to be less resistance than your body... That makes the "hot skin" a dangerous condition, even though the trailer skin is "grounded to the trailer ground (which may or may not be less resistance than your body).....