I'd be more inclined to have the pointy end hanging out the back of the tailgate rather than facing up into the headwind.
You can buy custom padded mounts for your tailgate from the usual suspects, or just use regular tie-downs and a couple of towels for padding as a cheaper option.
I'm sure there's probably an engineer or two lurking on the forums ready to correct me on wind velocity and optimum downwind curvature of your setup though.