forget the skid plates - go out and buy yourself one of those electronic dog training collars and put it on your bow paddler - hit a rock, and you hit the button - its called aversion therapy

scratches aren't too big a deal - I just "patch" them with a bit of epoxy to smoothe out the bigger/deeper ones - eventually, if there is a need, you can just recoat the bottom with resin - the fewer rocks you hit, the farther out into the future for that fix

I'd just go over the stems now, and add a little epoxy to any seriously worn spots that are more than scratches