I also do not need the additional
> rigidity in the hull since it is quite heavy and rigid enough from the two
> layers of, *ahem*, 8.9 oz. cloth on the outside of the hull.

All right Ed, after making a North Bay with one layer of 4oz on the bottom, and seeing the dings show up, and my daughters boat with one layer 6oz with another layer 4oz s-glass and no dings (my weight too), and another boat with one layer 4oz s-glass with another layer 4oz polyester (it was late,I couldn't stop myself)and no dings....it makes me glad to hear someone else enjoy a little extra extra.

go for the 3" minicell and 3m 5200 or silicone, you can make a template out of 3x5cards following the outer dimensions of the hull where you want the bulkhead to go. lee