The height is a good point and one I hadn't considered. Randomly pulling a golf cart's specs:
SHUTTLE 2+2 RXV
It looks like the "with canopy" height is 74". On top of a 6' 6" truck puts you over 12 1/2' and figure the extra height of the rack would put you at 13' - 13' 6". For me, this is the same as my camper's highest point.
But, I definitely like the idea of figuring out a removable roof. It looks like there are "convertible" roofs:
That would then put your height above the truck to 4' - 5' (for me, for a total of 11' or so).