This is the only other method I can think of that can reduce the shock and travel. Its just a set of pivot arms attached to a moving motor plate.

One of the biggest stumbling blocks is the steering linkage being able to adjust with it, which can be minimized by lowering the steering to the pivot point, but still needs to be compensated as it moves.

Trim changes only involve a range of plus or minus only a couple degrees, so some type of reduction has to be involved.

Another variable that becomes involved with the changing degrees is motor height which can also be considered critical.

The optimum pivot would use the prop as the fulcrum point in relation to the rear of the sponsons.