My advice is keep it simple,don't take extras you won't need.....just for the type of fishing/species you are targeting...A good Toweling cloth for wiping your hands is a must,unless you like scales and blood/guts all over your Boat! As is a Priest....if Bass fishing a de scaler is much easier/cleaner to use while at sea...make up any traces/end tackle at home,and remove ALL kit AND ancillarys from the Boat for a clean/wash down after use,if you don't want it to let you down next time.
Not a fan of tackle box's (tend to fly about too much!) on a RIB I use an army rucksack with lots of designated pockets,easy to locate what you need..and if it's Knarley or Wet stuff it into a Dry Bag.
A decent fish bag which can be left wet is a help too/I do use a cold bag/box for Mackies especially if the kids are aboard...or if it's a full days trip out.
Hope this helps