Congratulations on the boat! My advice: enjoy your boat. Things will spill with adults and kids. simtex is great, chocolate, wine, all comes off(personal experience).
If it doesn't? well then you have a memento of a fun day on the water. Put a dent in the rail trying to dock? Not funny in the moment, very embarrassing actually. But why get upset every time you look at it? There aren't many pontoons without dings and scratches, at least not those that are actually enjoyed.
All that is easier said then done, I know. But the sooner you get over the new boat the happier you and your passengers will be. Took me a while.
Now I still spend a ton of time cleaning it, first off I enjoy doing that, second I want to be proud of the boat when friends come on. You will also learn that most things that spill don't leave any mark. I can't speak to sunscreen because we really don't seem to have much of that, being in Maine.
As for things needed, hard to say without knowing how you are using it. I have a plastic ammo box (harbor freight) I filled with flares, zip ties, elec tape, screwdriver, pliers, air horn, knife. I also have a dry bag with extra set of clothes and towels.
The stainless pole holders make excellent flag holders on the ski rail. The yeti sidekick bag makes a great waterproof place to store binoculars, sunglasses, bottle openers, etc by the captains chair, just use some taylor fender clips to attach.
As said before seat compartments are not waterproof.
Also don't leave anything on the seats overnight. The water stain that will be left will eventually go away but I have had it take weeks depending on the weather. In the meantime your seat looks stained without even a good story to tell. Save the stains for the time you knocked over the wine glass while telling a story and blamed your wife even though she wasn't on the boat at the time (true story and it all cleaned up perfectly with no residual stain)
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