Quoted from Pin_Fandango:
always wondered how to remove the bottom panel? isn't it proved and inserted on the side of the cab? Really curious if you want to share the process!
You route the edge back so the bottom is exposed.
Knock out the bottom.
Replace with new bottom.
Glue and staple/screw new bottom in.
Add cover trim to create a new edge and strengthen it.
End cut plywood trim pieces makes it an invisible repair.
An alternative way is to completely slice off the bottom with a skill saw.
Add a new bottom that is not inset.
Glue and staple or screw the new panel on.
Fill the edge seams and screw heads, paint and decal.
If you staple you have a better appearance but a weaker job.
This is faster and works well as the bottom doesnt hold any weight at all.
But lacks the original feel unless you add on trim for looks.
I like screws for cab repair. They are much better than staples or brads and last forever.