You sure do know your stuff!!
I did some trouble shooting last night and traced the "Mem" and Stereo "On" wires back to the pre wired Dutch Connector (Male side connector) pictured above ^ and found that those wires were labeled "Ster" and "Memo". I then saw the yellow "ster" wire and traced it back to the nearby ground bus (Hydra Sports uses yellow colored ground wires AND yellow bus bars)
I'm a visual guy if you haven’t notice
Found the schematics (pdf file) I got from Hydra Sports for a project a while back and I'm missing the 1st page of 3 that would have this mapped out.
Pre wired leads at the duetch connector (Picture above) are 16g and are used primarily throughout the boat.