I like the idea of a side mount removable ladder. One that hooks to the rack then butts up against the tire.
Question though?
If you need a ladder to access the roof rack, how you going to store it up there and retrieve it?
Maybe something like 2mbb mentioned in that other thread from 07 (above). Attaches to the rack and butts against the tire for stability, folds in the middle for ease of storage and maximizing available space, and strong enough to be used as a traction device?
Once folded in half, could be mounted to the outside of the rear spare or can holders. If none exist, to the bumper in a horizontal position?
Even inside along a rear bulkhead via the wingnut system like the spare tire in a car trunk?
The latter concept would make it strong, stable, easy to access for use, could be uses on the rear of side of the truck, and keep it out of thieving hands and secure inside the truck

Could build 2 if you wanted duals and mount one on either bulkhead in the rear.
What does MUD think?