Pain in the asbutt. To do it right full acess to the inside is required. Grind/sand to raw glass 6 to 10 inches back on each side of damage and glass cloth 3 or 4 layers, use epoxy resins. Feather fill skim international waterproof epoxy filler (two part 1:1). Sand flat/smooth.
Paint with interprotect 2000 epoxy primer. Finish
paint as necessary. Move to outter side. Sand a squared section 12 inches for and aft if the cracked areas. Sand to raw glass. Epoxy glass 3 layers cloth with 1st (24 inches ) then 20 inches and 3rd 16 inches. Feather fill with epoxy two part waterproof filler (international), sand cosmetically smooth. Prime with 2 coats of interprotect 2000. Sand and
paint finish coat to match. You will probably have to paint the entire side lower panel to get a match. Glass, paint, filler, epoxy resins and sanding supplies about $600. 15 to 20 hours labor. Before finish paint by auto shop the repair should be about $2500; add another $500 for the finish
painting. Total estimate about $3000. I work on boats for a living. Also own a
Trillium 4500. Nothing is cheap nowadays, especially if you want it done correctly.