This would be the way I would it if I had to deal with the 5th wheel...
You can add the FOLD-A-COVER brand folding hard panels to cover this whole thing when not using it... The panels will fold up on top of the tool box just behind the rear window. I current use this fold-a-cover setup and the panels will still fold up out of the way to gain access to a front mounted larger tool box like shown here...
Even with all of these tool boxes install you can still have a couple of 2KW Honda Generators sitting in the open areas on either side of the hitch or use a less height tool box just behind the tailgate....
Photo from GOOGLE search...
This is what the FOLD-A-COVER installation looks like...

Roy Ken