O-clipper restoration- un-rivet seats or not ????

I am surveying my new-to-me 56 orlando clipper. I have read in an old magazine ad for them that they have styrofoam flotation somewhere.
They made aluminum and fiberglass boats. Mine is aluminum. It has enclosed
"dead" spaces under the front and rear seat benches and on the bottom
foreward section of the bow. There are small drain holes in the bottom
center to allow bilge water to drain to the rear. This would be the only place
the foam could be. Also the boat sat for 1 or 2 years full of water, avacatoes and avacatoe leaves and tree limbs. The avacato meat from the
disolved fruit had settled out on the bottom of the hull and has become a
thick hard sediment residue. A coarse scotchbrite wheel brings it up with a
little effort with no corrosion or pitting underneath. (yeah ! ) I am considering
cleaning the whole inside and maaybe painting it with epoxy chromate
(phosphate these days... ) My question is this ... the only way to get
into the spaces under the seat boxes is to drill out the rivets and remove the
top pans ( where your butt sits) . I am guessing the green crud is in there
on the floor surface too. Maybe styrofoam (????)
I am thinking of doing a water pressure wash to start out getting rid of the green crud - but the nozzle wont go in the drain holes.
Is it worth the benefit to unrivet the seats to get in there to clean and
paint ????? I have been an aircraft mechaanic so the riveting does not
scare me especially. Just trying to decide if it is worth the trouble.
Perhaps Racer11x or Tmartin56 clip or scenic might give me their thoughts
since they may have gone down this road allready perhaps !!!!!!!!!!
Thanks for any thoughts or ideas !
Tim in Orlando