We have a Grandy on a Shortbed Dodge 2500 QC. When we bought our camper we had the dealer install one of these under the overhang:
https://www.equipt1.com/collections/roof-rack-accessories/products/k9-camp-table
I also added a spacer in the bed made of 2 x 3's laying flat so it lifts the camper up 1-1/2 ". This allowed me to add a box under the overhang that is made from 1 x 4 which is really 1 x 3-1/2. In this box I carry a 8 foot extend and climb ladder which allows me to get up to my sea kayak to strap it on. The box could be used for anything you wanted.
The 1-1/2" spacer also lifts the camper so that I can make use of the space along side the camper in the bed. I store long things like kayak padles (broken down) or the struts for my inflatable boat wheels, plus folded up camp rug, extra oil, tranny fluid. It also gives me the clearance to mount my shovel under the overhanging side.
The other place I pick up space is between the truck bed and the front of the camper I use the space on top of the rubber bumpers to store my aluminum sand tracks that are wrapped in some rubber backed carpet from Home Depot. They are hard enough to get out of there and covered up so they are not on display to be stolen, but can be gotten out if needed. I've only had to use them once and that was to help get a 2wd Ford Transit out of the Baja sand.
I also have my gas can mounted on the rear of the camper.
On my previous FWC Ranger II shell, I had a spacer made of 2 x 4's on edge so it lifted the camper up 3-1/2" which gave me space to store my solar panels under the camper as well as some gear.
Hope you can use some of these ideas.