Here's a rough idea of what Tom and I are thinking about for mounting accessories on the heavy-duty hinges. We've still got some work to do on design details, so consider these just concept images for now.
Here's an example of a Hi-Lift carrier mounted to the hinges:
If you wanted to carry more than one thing back there, we're thinking about a base plate with a grid of mounting holes. The base plate bolts to the hinges, and then the accessory carriers bolt to the base plate. For just the Hi-Lift, it would look like this:
Accessory carriers can be bolted to the grid, in any combination that fits and clears the spare and the tail light. Here are a few examples showing other stuff mounted. On the left, some rubber "Quick Fist" clamps mount a military shovel. In the center, a bracket mounts an ammo can, perhaps containing a recovery strap. And on the right, a jerry can.
Mounting things as wide as a jerry can, or mounting a Hi-Lift plus an ammo can might cause interferance with the tail light when the tailgate is fully open, so for some combinations it might be necessary to install an optional stop in the hinge that limits the tailgate opening to 90-degrees. We made Tom's hinges to overcome that problem, they're designed with a wider swing than the stock hinge geometry so a jerry can will fit just fine on Tom's hinges, but for the heavy-duty hinges with the stock geometry a stop might be necessary for some combinations of accessories.
We're also thinking about a few other accessory carriers that would bolt to the grid system, such as a Rotopax container holder.
We're about to make up a prototype, but before we do, is there anything we've overlooked? And any other items that you think we should allow for mounting to this system?