This is strictly looking at the weight aspect:
My PUP's documentation states that the roof can support 150 pounds while raising and lowering the roof, and can carry 250 pounds while in the closed position. With my AC weighing 90 pounds per that manufacturer, that leaves about 160 pounds of cargo weight to be distributed while towing. Be sure to check with what your PUP manufacturer states.
I would definitely look at moving the weight contact points towards the side edges as the middle of roof and even the front/rear ends are relatively under-supported for this kind of task.