Do you pull out the rear bench or move it forward when you are using the bed?
How does the bed frame work when in use? Any photos of that?
How did you attach the rear shelf - through the panels to panel ribs?
I pull the full width bench out when the bed is in. The other benches could be used, depending on how many seats vs space you wanted. I attached 3/16" aluminum angle to the sides of the van with three 1/4" bolts. The panels sit on the angle and are secured to it with bolts.
Is the angle iron permanently attached the full length of the bed or does that come out as you remove the sections? In my van the full width bench leaves no room on the sides for any ledger for the bed.