I have never carried a spare. Walmart carries different kinds of repair kits for fixing a flat yourself. With your air fitting and air hose, you're on your way.
If a wheel ever has to be removed, road service must be called. It takes a tire air gun to remove lug nuts.
If you carry the proper tire tools, either steer tire, and either outside dual can be changed without having to removing the lug nuts or the wheel itself from the truck.
For steer tires, you need a hydraulic jack, the proper tire bars and a heavy hammer to break the beads loose if necessary. Then you soap up the beads, and remove the tire from the wheel while the wheel is still on the truck using the tire bars.
You can install your unmounted spare using the tire tools and lots of soapy water, air her up and you are on your way. I am not saying this is easy, but it can be done, I have seen it done. A guy built like you could do it easy.
Same proceedure as above for either outside dual. You don't need the jack though, you can drive the inside dual up on, say a couple of two by eights.
If you blow an inside dual, you can drive her in to a tire shop on the outside dual, if the inside tire is not coming apart and doing damage.
If you decide to carry an unmounted spare, you figure a way to attach it either to the back of the sleeper or the top of the frame. Use a lock too.