Torsion bar hold down/latch down problem

[MikeHead]

I have a 97 2720sl all 4 bolts holding this Torsion bar/ latch down bracket fell out. I've tried new 4" galvanized wood bolts same problem. I believe water infiltration has rotted the wood that the bolts screwed into.
Was wondering what the walls are made from and just how thick they are?
Anyone else had this problem? And if so have you found a fix for this problem.
Right now only thing I can think of is using much longer bolts.