Momule
The idea is almost like a car bumper or frame as it pertains to dispersing the bounce and stress of the motor on the transom. I try to allow just the right amount of bounce while keeping the motor in constant pull back to the trailer to disperse the energy. The result of my saver would be different for each boat, the location of how the boat sits on trailer and the location of the axle etc.
I have the same problem in my home town of where to launch the boat at what ramp because of the decline. In one spot I would have to get half the truck in the water and the other it doesnt even come close. The solution for me was to lower the boat as much as I could on the trailer while keeping a safe riding height for the motor when moving. With the transom saver version I made it keeps it a perfect height to where I could launch without worry and still keep the thought of being safe.
For one ramp it declines so slowly that I just went ahead and purchased two 12 inch trailer extensions and connected them (price was a total of $15 which is why i didnt just buy a 24inch). I would attach the extension at the ramp in 5 minutes and it would allow me to stay just enough out of the water that I could launch safely. I even had FWC / Local Police watch me and come ask me what in the world I was doing. After explaining they went and bought the same set up in order to launch their boat at the same ramp without submerging their trucks haha. I only go to that ramp 5-10 times a year so its not a hassle.