Karlf - sorry for the delay in getting back to this one. Holidays I guess!
I am quite familiar with moldless construction and its approach and limitations. When we look at a gantry think of the loads and forces in the wing spar. You'll find some interesting approaches in unpowered aircraft (read sailplane) that use composite spars, fuse, etc. Check out the build of the Pioneer 3. (Jim Marske has spent a lot of enginnering thought and effort in using carbon rods as the spar caps -- top and bottom of the spar.) Such is the types of "engineered approach" to get a well structured gantry. Remember the loads on the gantry are going to be resulting from the router cutting forces and the router weight and torque from its position as well.
Re the Cozy - A great plan to do all the bulkheads etc with a cnc and the bits and pieces. DIy Boats are moving in that direction - especially class racing - like the mini-transats.
You might like to check out Vectorply (google) they have a bit of software the Laminator you can work layup schedules loads etc.
If I'd ever get my
pen to work - I'd finish that book and share the hows and whys with you on a neat approach to moldless construction that takes it one step beyond.
Jim