I saw the Groco item. I'm trying to find the source for the stainless plate, which is U bolted to the seacock, to give some lateral shape to a 'push pull' rod or cable in line with the path of the handle. I may have to get creative and make my own plate. But I have seen (over the past 30 years or so) a drop in place part. Just can't pin point it.
The reach rod idea is not doable in this case. Not enough clearance on the side of the battery box to make the 90 degree transition. Looking for something like this:
Marineparts.com - REMOTE SEACOCK OPERATION ARM But with a firm base to align the handle to as it 'throws' open and close.