I've gotten to the bulkheads step of boat #3. I'm not building it for myself, and have tired of installing wood and fiberglass bulkheads, so I'm thinking about going with foam bulkheads this time. How thick should foam bulkheads be? How are they secured in place, and how much should I expect to spend to outfit a 22" wide stitch and glue kayak with 2 of them? Thanks for any advice on this.

-David