The ideal would be to disassemble it and put the pieces into boxes.
Alternately, remove the carriage from the gantry and the gantry from the frame — pack all the parts carefully, and be sure not to lose the power supply.
I just moved 5.5 miles. I transported my SO3 XL In the bed of a pick up truck. It was flat in the bed and surrounded by other objects so it wouldn’t move around in the bed.
If you were going to go a similar route I would put zip ties on the rails to prevent the gantry and a-axis from moving around.
I moved mine a few hours drive recently by bolting some 2x4 and plywood to the wasteboard to make cradles for the X beam and Z using my workholding to clamp it all down, this meant I didn’t have to remove cabling etc. as the drag chains had enough flex. I removed the remaining V wheels so that the Y rails weren’t carrying any load.