I'm in the process of filling and sealing about 70 or 80 holes in the headliner in #45 , just use polyester filler .
I think a bright wood overhead would be too much , but I hate all teak interiors with no paint , prefer wood accents and trim . It would be easy enough to do , but why ?
Boats dont need to look nautical , like some restaurants do , because they are nautical, so don't get too cutesy and clever or you will end up with something like that abortion of an Ariel that had the deck raised , etc., etc.
Remember the KISS and 'if it ain't broke , don't fix it' rules , especially on small boats .
Have you thought of handrails on the inside matching the ones topsides , just drill , thru-bolt and plug both sets .