Speaking of Headliners

Hi, Folks. I usually work on CAL 25s which have no cabin headliner. It is therefore very easy to anchor through-deck fittings with fender washers or backing plates. However, … I am now doing some work on a CAL 2-25 (AKA Mk II). We are bringing some lines from the mast back to the cockpit. Aside from the lack of space for deck organizers on the deck, there is another problem. There is an interior headliner that appears to be plastic or vinyl and curves around to the interior hull walls. Does not appear to be removable. In the original construction, it appears that they fastened exterior handrails by coring ¾ inch holes through the headliner to the deck plywood, and anchored the fasteners at the plywood that way (then put plastic plugs in the holes inside for decorative purposes). There appears to be a gap between the liner and the deck plywood. This tells me it would be difficult to epoxy the deck holes and redrill in the proper fashion without doing more ¾ inch holes in the headliner so we could seal the bottoms of the holes at the plywood to keep the epoxy in the hole. I was wondering if anyone has experience with the 2-25 who could tell me how thick the deck plywood is, and whether the gap between the plywood and headliner is everywhere. Is the headliner strong enough that I could put backing plates (for clutches, organizer and a deck winch) under the headliner? This would make the bolts awfully long. The info will assist in the “design” decisions. I was just going to help a friend with a quick job, but we know boats don’t act like that. Right now, we would be looking at another 20 (or so) big holes in the headliner. Sigh, but Many Thanks Charlie Annapolis