Probably plenty you haven't thought of, but nothing that some pocket money and wits-about-you won't cure.

Twice the ( cash) money you planned to take and half the clothes. Some small denomination bills, USD. 1's 5's 10's 20's

C&I cares not whether your cooler contains vac-sealed or ziplocked stuff. It is your stuff, not theirs.

Ketchup, mustard, pickle relish, soy sauce, duk sauce, chinese hot mustard... all individual packets saved from take out .. can be an ace in the hole in a charter galley.

Everyone does this for the first time, their first time.

They do sell food of some kind nearly every place you'll moor in the BVI. Don't tackle Benures Bay on Norman Island ( anchorage only) if you aren't provisioned.

No one can do this for you, and your paid captain will be happy to make sure you have a great time. Please try to make sure he has fun, too.