You should look at attaching that prop to a genset while underway.
Lots of ‘free amps’ for little drag...
I considered some kind of belted-in friction clutch deal, but the space if very limited and it would severly limit engine room access. But I’ve seen some great setups that do that. My Hurth gearbox recommends putting it in forward to lock the prop as doing less damage than freewheeling.