Questions...
Was this boat ever in a crash?
Are you experiencing heavy stress cracks in any one area in particular?
You say the bulkhead is splintering, wood or glass?
Have you made any structural changes (like cutting holes for stereo speakers and whatnot)?
Does this boat have a false floor?
I have some suspicions on what is going on, but without the touch, smell, taste and see, it would all be speculation.
The walk through section has broken free from the bottom half of the hull, seen it before.

Good luck, the shop I worked for for a while is no longer in business in San Diego....So I'm no help.

GT