Rust question

[sacustomcycle]

Is there any hope for a cab with rust like this? If there is, what would be the best approach to fixing it? I haven't had any luck finding a replacement cab around my area that is in any better shape. Does anyone ever chop the whole top off and replace it with another one? The floor of the cab isn't much better than the top. The PO was at Corpus Christi on the coast and the salt ate it up. Surprisingly, the bed and frame are solid.