Tim:
I have drilled through the deck and bolted items down. The deck is thick, 1/8 to 3/16" maybe a 1/4" and then under the deck is a space that is filled in then under that space is the headliner that you see from below. So there is a gap between the headliner below and the deck topside. Some areas this gap is solid, some areas it is filled with resin some areas it is hollow. So the best way I have done this is to lay out your mounting plate and drill a small 1/8" hole down into the deck and through the headliner. Then from below, use a hole saw and drill a hole big enough for a socket head, washer and nut. Drill this hole into the headliner, 1/8" and the disc of the headliner will pop out. Now you can either see the deck, up there another 1/2" to an 1" or you will see filler, or it may be solid. If solid, bolt and go, then cover with a teak plate. If hollow, or foam, clean it out and get your washer and bolt up against the solid deck. Again cover with a teak plate. This is how I have done this and how I have seen this done. Obviously you need to also drill out the 1/8" pilot holes to the bolt size holes for mounting the hardware.
Some where I have photos for this headliner and space and mounting bolts. If I can find them I will share.
One more idea. Have you thought about mounting the raft under the nav desk? This is where we have ours on the 35 and I know the 38 has just as much room.
Hayden
