Hull flex / stress points of solid bulkheads - it's total nonsense. The stripper hull is stiffer than glass kayaks. I put solid bulkheds in (5) strippers and two S & G's. Every boat show I go to there's plenty of them. there's probably thousands out there. Nothing has ever exploded. Most quality glass boats have glass bulkheads.

Solid bulkheads makes a stronger boat. If that's what you want to do, do it and don't even consider any flex issues. The only reason to do a foam bulkhead is to save work, however they do a lot to help streghten plastic kayaks where flex is a major issue.