LtS:
I will let Steve (Sandcruiser) answer for himself, but would like to interject, if you don't mind...
AutoHome tents are designed to mount simply on a couple Thule or other aftermarket crossbars, the same as you would use to carry your canoe, kayak or surfboard. The tent is mounted with a set of sturdy U Bolts, securely bolted down, which slide in tracks on the underside of the tent - allowing front to back adjustment. The rack system transfers the weight to the structural parts of your car's roof. Like vehicles, roof racks carry a dynamic weight rating, which defines the tested limitations of the rack system when the vehicle is in motion. Most racks carry a maximum 165 pound dynamic rating, which means the rack can support 165 pounds of weight while driving down the road. AutoHome tents weigh between 95 and 155 pounds, so the rack system can easily handle the weight. When you are parked and camping, this is a "static load", much more gentle and the racks can easily handle this weight.
Every vehicle manufacturer has a specification for maximum rooftop loads while operating the vehicle. These standards may also vary by country. Always check with the manufacturer of your car and of your roof rack to determine the applicable weight limitations as they vary from vehicle to vehicle.
Several new models of the hard top tent can be rigged with a kit to carry additional loads - subject to the restrictions on total weight stated above. Surf boards should be no problem. I would not recommend putting very heavy loads (like full fuel cans) directly on the tent top. This could exceed the weight limits for the rack. Better to mount them on a swing away carrier at the rear of your vehicle.
These tents are very strong, and have been used successfully in very windy conditions.
M