been out for a while. Thanks for the comps. When I'm building I tack glue the parts with CA, then run a beed of 30min epoxy at all the joints and seams, then seal with epoxy inside and out. Depending the wood you are useing, with the aircraft quality birch, fiber glass helps a lot but can be left off. if you are using lite ply or door skins I would put 2-4oz cloth, with the epoxy.
Inside of my hulls at the points where high stress takes place I use some 2 oz cloth to help hold it together.
40" X 20" is a good size, make the sides between 2-1/2" and 3" high