Sell the extras when they book.
Offer lunch, fish cleaning, ice, or anything else you sell. Price each one per booking, per person, or by the piece, and collect it when they book or at the dock.

Charge for them the way you already do.
Add them once to a trip, and they show up every time someone books it.
PER BOOKING
One price for the group
Fish cleaning, a cooler, or live bait costs the same whether two people come or six.
PER PERSON
A price for each guest
Lunch or drinks for everyone aboard. The price goes up with the number of guests.
BY THE PIECE
They pick how many
Bags of ice or extra bait. Set a limit if you only have so many.
ON THE MANIFEST
Your crew knows what to bring
Every add-on prints on the manifest under what to have aboard.
Add-on questions.
Can I make an add-on required?
Yes. Mark it required and every booking of that trip includes it. If it's priced per person, it's added for each guest.
Can they pay for it at the dock?
Yes. Set an add-on to pay on the day. Guests choose it when they book, and you collect for it at the dock.
Can different trips have different add-ons?
Yes. Each trip has its own list, so a full day offshore can offer different extras than a half day inshore.
