Dan,
You could easily do the Eureka Dunes road with your truck @ 26 pounds and off-road trailer at 1/3 pressure. Just have a way to get all those tires back up at pavement. With the route we took, by design, we could stay at low pressure almost all week, about 250 miles, with little pavement to worry about. The only part paved was around Darwin for a while, which if you stay slow enough (circa 45 mph) is not deleterious to your tires. Modern E-rated truck tires (mine are rated @ 3860 pounds, ea.) are oh so much tougher than their earlier counterparts of decades ago.
jefe
**EDIT: One thing that would increase the 'off-road-ability' of you toad would be the application of a pintel and hoop. This is my wood gathering rig: 1955 Bradley trailer that I've had up to a ton in, and my 1999 Jeep XJ. It is a Neanderthal set up but has a LOT of flexibility. If you don't keep some tongue weight it can be clanky:

