Occasionally the need to car top a hull or two arises. A hitch mounted canoe carrier is great for aft support but too narrow for two hulls. Solution, unbolt 16 or 18 inch top cross bar and swap in a piece of unistrut. Bolt tight and voila, another anchor point. This is on a Caravan btw.
No elegant front anchor system discovered yet. Just way too much plastic to deal with.