I am looking for replacement seats. I had the idea of using some marine grade low back seats. They are made for the environment, sun, water, etc. Granted not to many marine seats look like car seats but I have seen a few.
I was looking at the seats from Summit that are the hard plastic high back racing style and the covers are vinyl and foam. Probably not the best padding but pretty indestructable. These also work well with a harness type belt. The replacement covers are pretty inexpensive too. These run about $75 a seat with covers.
I think anything is better than what I have now!