Hey Stoty, I'd be inclined to use that skiing pole mount. Any decent slalom skier worth their salt will put more strain on that spot than you can get yanking a tube. Having spent a few summers getting paid to teach skiing and yank kids/teens/adults around on evertything from tubes and skies to kites, 6 person pyramids and barefooters etc, I feel pretty confident if it's rated for a skier, it'll handle the tube.