Thanks for all responses,
I do know exactly how the old headliner was installed, because I removed it. The entire interior has been removed, it is basically an empty fiberglass hull. The headliner was vinyl cloth covering 1/4 inch plywood. it was screwed in place into 3/4 inch plywood blocks that were screwed directly into the cored fiberglass fordeck (from below of course). this created a small space for wiring and to hide the connections of the upper parts of the bulkheads to the ceiling. The sidewalls were covered with carpet, which was glued directly to the fiberglass. This has been removed, and I will probably use foam backed Vinyl in its place. Besides wood, that is basically how all the new vessels I saw have their interiors finished.
What I'm tring to do is purely for aestetics, the old headliner had teak trim covering the seams in the ceiling. these seams had screws directly through the ceiling and then covered by the trim. Since the new ceiling config will likely be different, I'm trying to do it with just pieces of headliner using concealed fasteners and no trim. I think I may have a soltion, I might use high effort snap fasteners. I might also screw through the panels near the ligh fixtures, which will be covered by the fixture itself. This will be a while, as I have 2 very small children(a 2 yr old girl and a 3 month old boy)an basically no free time. But I can plan, and if I have the design mostly figured out by the time I can get to work, that's half the battle.
