Hydo Mike has a thread showing how to do a skid plate. There is another approach to this by finding a donor bottom. Now this will not be a easy task but it can be done. The ABS responds pretty good when heat is applied. My plan is to heat and cap the bottom of my tub with a destroyed tub. The lower bottom of the tub is in pretty good shape.
Attachment 3429
It is in its initial stages right now.