It's much easier faster cheaper just to tie down with dock lines on the rear cleats, at least on t he , imhe.
You can tie down from land
The dockines are already on you cleats fter docking
No hull damage worries
A truckers hitch will give you a nice 2:1 advantage to get nice and tight.
I just throw a strap over the cockpit, aft of the genoa fairlead tracks, where it's smooth. That's just in front of the goal posts, if memory serves, and the hooks wrap around the bottom of the trailer frame channel and hook there.
The Mac Bump works great!! I was fighting yesterday to get the boat in the right place on the trailer, backing in and out, and finally rolled up onto lever ground and just barely tapped the brakes and that is all it needed! Now the chain works great too. Its not too short at all