Looks like a gadget that will be useless after 4-5 trips...The description says it's adjustable for different launch ramp depths,, which means it would need to be changed for different launch ramp depths and angles, seems like a huge hassle to me.
Key to loading is proper trailer depth, which you'll need to figure out for your boat/trailer. On my 18' Vhull it's the tops of the trailer fenders lapping at the water's surface, on my 14' jon boat it's the rear tips of the bunks at the water's surface. Myself, I sight center of the boat to to the trailers winch stand to line it up, making steering adjustments during approach, usually starting 50 yards back.
Agree with the others, practice during the week when the launch ramps is deserted, so you get the hang of loading, then throw in some wind and or current. 99% of the time I load under the boat's power, but if it's real gnarly, I'll dunk the trailer close to the launch ramp and "walk it onto" the trailer