Ok. Channge of plans....it will be better to just make multiple spot repairs with epoxy resin and glassfiber powder. First I would repair the surfaces top and bottom sheets and then the aereas near the rails. All the spots have to be well grinted 80 grit..or 100 and well cleaned. Tru to make the epoxy thick as peanut butter... And again grinted when epoxy is fully cured with 220 grit and 500...
Second stage of The areas on the rails.mask well top/bottom ..just use two strips of thick plexy glass clamped along the damaged area and use same epoxy with filler but not so dense. Like making a mold.
Then again grind as said b4.
Profiling the rails...just grind to straight profile the areas...
Offcpurse buy a new fin..aactually two..
....and if you want for coral use...you will ofcourse make same damage....
Now if you want to make lamination...as initially said...it will take you so much time..dirt...to take off the ptex....and for sure woull have pieces of fiberglass off...and then again grind the fiberglass to reach the woodcore..is almost immposible without irregularities that offcourse will not make possible any king of top / bottom sheet to be applied smoothly...sorry...and offcourse grinding the epoxy ptex fiberglass you will need full protection....PPE...as chemical war....