need bed floor help

[Jmiller022]

This is the current bed of my truck, and i am wanting to toss a nice piece of plywood in there, but I have a couple of issues.

My first issue is the rust/surface rust in the back corners and on the angle pieces. if i wire wheel it down and then throw on some good epoxy primer will it be okay? or if the angle pieces are replaceable I may just buy new ones.

my 2nd issues is the PO installed the fuel cell and the vent fitting and the return fitting both sit up above where floor would sit flush. it doesnt seem that i will be able to drop the tank an inch or so to alleviate the problem. So maybe are there smaller fittings I could use (height wise)?

Thank you for your help.