Frames finished, should I paint or what?

[Corrib]

Guys, I am building a Trailer sailer plywood over oak frames. all of the frames are ready for the stringers and chines. Should I paint/ oil the frames at this stage, before the stringers and chines? In other words should I finish as I go. If so, whats the best material? I would guess epoxy but is there anything a little cheeper?

Thanks

Kevin