The important thing is to keep the bulkhead from making direct contact with the hull. You don't want a hard spot and it's a point of entry for water
into the endgrain of the bulkhead.
We just shaped the bulkheads and furniture so it had aproximately 1/2" minus stand off from the hull. Then glassed in the bulkhead with at least 6' overlap onto the bulkhead and hull. Did both sides for the bulkheads, usually single
sided for the horizontal furniture pieces. Laid up at least three layers of matt and cloth using polyester resin. It's held up without a problem for over 35 years and three trips to SoPac including a hurricane
. I tried the foam thing but it was a royal pain in the butt to mill the foam, cut the bulkhead to fit and keep the foam in place while glassing. Doesn't seem to be worth the effort.
Another amateur builder
did drill his bulkhead and threaded cloth through the holes and then glassed over it. Seemed like a lot of hassle for not much return. Think you'd be further ahead to use Epoxy
resin to bond the bulkheads.