Master air pallets were standardized in the early 60s at 108"x88". Later when commercial freight developed their standards they kept the 88" length, but widened the pallets, and containers to 125" to fit the fuselage width of the DC-8 and 707. Resulting in the 125"x88" "A" pallet. The military pallet became the "B" pallet at 108"x88". Later when aircraft got even wider the pallets grew to 96" by 125, or the "M" base. So those are your three basic aircraft pallet, and container sizes. Height is another consideration, the military uses a 90" and a 60" standard cube, the "ISU" which I think, height wise would suit Traveller better, 2 stacked would be the height of a deck plan square.