I too have a Trafalgar hull from OTW. I'm making slow progress on the kit....only due to my lack of free time!
This is a very nicely detailed hull with Bob's usual excellent glass-work. I decided to build the hull in much the same way as Steve Warner did with his OTW HMCS Victoria (ex Upholder), which he very kindly documented in an article for the SCR a while back.
Essentially, the upper bow and stern ends are cut off the (upper) hull and bonded the the lower. The middle, upper hull more-or-less then needs something to keep it from spreading out....so I have cut some ribs, one for each end. I used my favorite material, G-10, for this. Once glassed in, the upper hull section is *not* going to spread.
Installing the stern planes/rudders is quite straight-forward. Same for the sail.
This is quite a 'beamy' hull, which should make it quite easy to fit a dive module to it and then trim it out.