If it was my project
and I wanted the job to last I would glass the entire unit with something like Dynel cloth, shoot with multiple coats of a Duratec high build primer, sand fair and smooth, then spray gelcoat
or a quality two part paint
. The issue with just plain wood
is that the constant expansion and contraction will alway open up small voids, then water
gets in, and you can figure out what happens next. Two layers of Dynel will be suficient
to stabalize the panels
and reinforce your joints all at the same time. Additionally all end grain on the ply should be thoroughly epoxied to prevent water
intrusion there, two coats minimum, I prefer three.
If you need to see some pics of this type of work
let me know.