I understand that the transmission on my 2GM20F Yanmar doesn't like to have the shaft spinning when underway, and that I should not put it in reverse to lock the prop.

I am considering a feathering prop, and some way to lock the shaft... it is the latter that I have no idea about. If I use some sort of wedge or something, I will need to cut an access hatch into the engine compartment from the quarter berth to get to that part of the shaft.

Is there some sort of remote mechanical system that I could lock the shaft with?

Ultimately I realize that a feathering prop is expensive, but the flip side is a slight gain in sailing speed and an even lower chance of catching kelp when I sail through the stuff. (my full keel boat with the prop in aperture pretty much glides over kelp now)