I had a green penobscot that wore through to where it was showing white.  I put skid plates on it and it could have been used as a ice breaker after that. The skid plates I used were over 1/8 thick and that was plenty. I used the canoe for a couple of years after that and the skid plates did not show any wear.  As far as what to do with your boat use it as long as you can carry it then sell it and buy a lighter one.