+1 for use of kevlar on the bottom.

I use this also already for years because of the high abrassion on my sharp assymmetric hulls. And by the way, it is not much harder to work with then other type of cloth.

On the bottom I use kevlar in ribbon format which covers exactly the sharp end of the bottom. To finish off the wet kevlar-laminate I always use PVC/tape (which I take off after hardening). The sand on the beach will sand it off very smoothly (only shells can make a hairy surface).

With regard to your damaged trailing-edge of the rudderblade, I wouln't suffice with some filler or so.
Sand it off with a overlapping "welding" section of about 4 cm on the sound part of the rudder. reconstruct any core if necessary and start laminating.
Do this for both sides of the rudder. Finally sandoff a nice sharp new trailing edge!