If that was mine I would look into blasting that front panel and floor about a foot up the wall and back on the floor so you have clean metal to weld the patches on. The rest of the floor hit with a wire wheel on an angle grinder then the acid wash. You can then prep and paint over that with anything you want from the trucks factory color (lot more prep) to bed liner (low on prep).
Once blasted you will see where the thin places are and what needs to be patched.
As said you can get flat metal sheet to fix the front wall if no one makes a patch as it is flat across. You could do an over lap weld with plug welds (punch holes in both panels) then use seam sealer on the seams to seal them. I also use weld thru primer for some protection between the panels.

On the bed floor if you can find a section from another truck from the center of the floor that is good use that to fix the front bed floor. It would have the ribs and if butt welded you would never know it was fixed but I would do the easy way of plug welds again and seam sealer.
If you wanted to crazy you could then finish it off with body filler and paint the trucks factory color (lot more prep) to bed liner (low on prep).
Floor, rocker, rear door post, cab corner all plug welded with seam sealer top & bottom, the spray paint looking stuff is the weld thru primer.

2 coats od roll on bed liner top & bottom

So you know I am not talking out my ......lower left door inner & outer patches




And that was all before using a long bed metal ribbed floor to replace the wood floor for my short bed flare side


Note with the front panel sitting on top of the ribs no more water & dirt will be trapped. The style side floor had bed liner on it and I saved it, will touch up with roll on when I paint the truck this spring.

There was a lot of work put in to make this happen to look factory stock with moving front cross member and fitting the running board braces to re-forming the rear flare side bed panel to fit the style side floor, the front bed panel had rotted across the bottom and used part of the removed bed cross member to fix to name a few.
Just wanted to show how it could be done and to kick some in the butt to start on their project.
Dave ----