Which raises the question of how much specialized ground support equipment will be needed (e.g. GPS guided vehicles to open and close the tail cone on Boeing Dream Lifter).
Do you want a vehicle that can simply lay the odd-sized cargo n any concrete ramp? .... or something that is thousands of pounds/kilograms lighter, but needs its weight in specialized ground support equipment?
At the exotic end of the scale, I can envision an overly-specialized cargo plane flying 3 missions to deliver a single exotic piece of cargo. Flight number one delivers specialized ground support equipment. Flight number 2 delivers the cargo and flight number 3 moves the specialized ground support equipment to the next destination. Holy "extra flight hours Batman!"
OTOH, the ideal military transport lands, and opens the rear ramp. It drops an anchor and slowly taxies away from the anchor, which pulls the cargo out the back end. The transport then (hydraulically) closes its rear doors and flies away.