Bike racks actually work better as a tow hitch attachment, easier than lifting up top. Skis and snowboards are usually roof items, but I also think a hitch attachment though hard to find is even better. I bet the third item usually up there is a rocketbox for extra storage. Again, hitch mounted options for storage exist and are great for vehicles like a Jeep. Occasionally strapping down something to move, just rent. Biggest issue I see is longboards and paddle boards, kayaks or canoes. I just can't see any solution there.