Hi Barrie - when redrawing the Tour Master built the same way (same designer - Ted Stinson) used a deeper keel and Les Rowells idea of doublers between each former - that build worked far better for me. There is also a build blog on Mayhem - plus a refurbishment of a really well built version - some great pictures on there .
Between the instructions & plan there should be more than enough detail of all components with the exception of the planking which should be easy enough to create using old cereal boxes, - the lobster traps are not shown on the plan itself but are easily made. The smaller version sent uses a different type - details are all included somewhere in the plan or instructions
I would agree with using liteply frames & keel - but balsa planking with a coat of either type of resin even without GF is fairly tough . There are many other other alternatives available there in the UK - roofing membrane , nappy liners, the material used to strengthen dresses, tissue & dope etc etc - plus you can obtain the water based epoxy resin (which is no longer available here
Apologies if Im teaching grandmother.