So basically 15k plus parts.
Just the welding and panel replacement labor is $15K? Plus parts? Hello?
Unless I'm missing a huge amount of rust-out, the driver's side fender seen in your first posting could be repaired with a patch. I understand why the body shop doesn't want to mess with anything other than full panel replacement, but that's why your estimate is $15K+. I'd want to see pix of both front floors and the entire rear floor, but a reasonably skilled guy with a welder can rehab the sort of rust seen on your truck without total panel replacement. Given some of the ghastly panels being sold, there's something to be said for retaining all the Toyota you can.
For the repair $$ specified, you could buy a very nice welder, some classes at a community college, and replacement panels and steel to your heart's content. You could then pocket the remaining $10K. You may not want to do bodywork for other reasons, but you might consider it for financial ones.