weave on the rudder looks ok.. id guess its just adhesion with the paint, your proposed epoxy filler should work perfectly as long as you're not overly fussed about a colour match (I wouldn't be!)
If you have space in the dagger board housing i would put some unidirectional fibres and weave over the top, if you can't fit it then your best bet would be to do a single layer of weave.(again if you have the space) If its wearing down in use it wont have suddenly lost loads of the fibres so likely wont fail immediately (but may eventually fail) however if some of the weave is wearing is the cause of the lack of fibres then there should be space to put some carbon back where its worn away....
if you decide to leave it then worst case scenario is it fails, i'm pretty sure there are people in the class with moulds for dagger boards that would be a bit higher aspect so i'm sure the class would be able to help you build a board and shim as a sticky weekend project if it came to it
glad you're making progress.
Alex
