I've heard that if the flat is on the front, you can swap one dually and drive slow to a permanent repair.. If the flat is on the back, leave it and limp to a repair. Correct me if wrong.
Or call AAA. That's my solution.
AAA rocks, but if no cell service....

I like having the spare, even if I cannot physically change it another person may come by who can. I have been that person in the past.

Best argument for having a spare and the tools to change it I know of. ( Likewise a basic tool kit and spare fuses, etc. A good Samaritan can be a GREAT Samaritan if the pieces are there to complete a fix.)
Not to mention I love the look of the spare on the back of a PC. Classic and distinctive. But no accounting for taste, right?
As a 'no other options' solution, swapping out a tire from the rear may get you to a repair shop. If you are travelling fully laden, I would transfer weight to the front and intact dually side. Transfer weight to the towed vehicle/trailer if you have one. * Dump all tanks. Remember, this is a 'no other options' scenario, OF COURSE you should NEVER just dump tanks on the side of the road. But if you feel your health or safety is at risk, do what you must.
*send passenger in toad with the bad tire to get fixed? If alone, and if leaving everything on the side of the road is OK, take the bad tire to get fixed with the toad. Having a spare vehicle obviously makes things easier...