Other more qualified forumites might have different ideas, but I would use some marine epoxy filler, let it go off, then sand to match the profile of the rest of the area.
Stuff some expanded polystyrene in the hole to support filler and then use some glass fibre paste, which has stranded glass fibres in it. Sand to shape and paint. It's only a decorative corner and you just want to make it watertight and look OK.
I repaired a badly damaged dinghy using the same technique and it's still going.
Use any paint you fancy. Marine yacht enamels are not very tough. I found Berger domestic gloss paint to be very hard-wearing. Don't waste money on 2 pack paints.
(I never did paint this repair)
If its accessible from underneath patch up from below with glass chopped strand mate and ordinary polyester resin. Then fill and fair from the outside .