The subtlety of vehicle liability insurance is that it covers damage done by the vehicle, not the owner or operator. It does not provide liability for you as the owner of the vehicle, nor for the area surrouding the vehicle, e.g. a campsite. The example about liability when someone trips on an RV's step is a good one for the lawyers - it's squarely in the gray area between vehicle liability and the owner's personal liability.
If the person tripped because the step broke, it's probably covered by vehicle liability. If the person tripped over the wine bottle you left on the step, it your personal liability and probably not covered under the vehicle insurance. An easier example is if someone trips over a lawn chair on your site - the vehicle is not involved in any way and a standard vehicle policy provides no liability coverage at all. In that scenario, you (the renter of the campsite) are persoanally liable. If you have home owner's or renters insurance, it will have a personal liability umbrella that covers you away from home and you are covered at yoru campsite. Fulltimers don't have that, so they usually purchase a rider on their RV insurance that provides personal liability coverage while using the RV. This rider is typically called "vacation liablility" coverage and isn't very expensive.
I don't purport to know how boat insurance is written, so it would be wise to check with the agent about it. Suppose someone trips on your dock line? The boat didn't damage anything, so did the injury result from operation of the boat or is it related to the dock? Or to the person who tied the dock lines? If the dokl is at your home, you are covered either way, but away from home? Good questions for the agent (and make a note of the answer, date & time, in case the underwriter says different at a later time).