Chris,
I finally got around last week to removing all the teak battens from the headliner on my T40 to explore its construction. What I found was that the entire hard GRP headliner had been installed in one gigantic piece, including down the cabin sides, with the teak battens serving mostly a cosmetic purpose. However, I also found that someone in the past had taken what I assume was a multitool and sliced the front portion (from the hatch forward) into smaller sections in order to facilitate installation of the deck organizers. They had sliced fore and aft along the outer sides and athwartships along the channels that are normally covered by the battens. The newly formed panels had then, after the work was done, been refastened with countersunk flathead screws and the cuts neatly hidden under the re-installed teak battens.
I hadn't been expecting this and am now considering whether to do the same work on the portion of the headliner involved in my project, or to leave it alone, re-install the battens, and go the less work-intensive but also less aesthetically neat route of drilling access holes for the track bolts through the headliner and then using off-white plastic plugs or teak strips to cover them.
I can take photos if you wish. Of course the headliner construction on the 3800 may be different from that of the T40.
Cheers,
Carter Brey
T40 Lyra
City Island, NY