If you are worried about a certain person suing after falling out and getting worked either dont take them, or.... provide them with a cement pfd , much cheaper than insurance
I have american family business liablity and homeowners insurance, I insured all my climbing gear, but I was told they MAY want receipts in addition to the pictures i provided, like I have receipts from 10 years ago... Also if you are going to insure some boats, and all that is needed is photos, you might as well invite all your friends to bring over their gear and photograph it in the garage with yours.
Scott