Does anyone make a keel guard or equivelent to fit a cat hull, or has anyone had success using one on a cat hull? We mainly boat on a river and the shore is mostly gravel.

depending on the speeds of the app - IMO alot would peel off at high rate of speeds. I have install many in my day on bass boats when my shops work on all the major branded engines. Prep work of the hull and very clean was always the key for installing them so they stayed put.