We haul two karts in a 6x12 enclosed. I built a shelf that my son’s Cadet rides on, height is slightly higher than the kart stand. This lets me load without help. My kart rides on the floor. Generator between shelf and side door on the right. Three shelves up front for rains, chairs, tie down, etc. Rolling tool box and trailer jack strapped to the bottom shelf. Canopy, extension cord, and trailer spare on e-track on the left wall.
When the girls want to ride I can get the kid kart in the open area between the shelf and the tool box. Kart stands, bikes, scooters, cooler, portable grill all ride in the back of the truck.