: Is that 4mm glassed-in bulkhead
: strong enough to take the pressure?

I always glass both sides (4 oz glass) and use fillet/tape on both
sides too. I have used a dihedral bulkhead (top is further forward
than the bottom, centre is further aft than the sheer) which I find
gives me more toe room and I believe is also stronger. I don't use
foam, but doing so in a decent thickness would spread the load, reduce
shock loading, and make it a lot harder for the type of mishap described
by Glen to occur. I glass both sides mainly because I don't trust just a
sealing coat of epoxy on its own to remain waterproof - and the face of a
bulkhead is difficult to repair once glassed in. Again, a layer of foam
will mean your feet aren't grinding mud and grit into the surface, so the
epoxy will last longer.

Andy