What an awesome analysis!!!
I'm open to suggestions for any tow mirror (aftermarket or OEM) that will retain full functionality of the DL3. Looks like the 1786 model is out of stock anyway.
If you or anyone has part numbers for OEM or known PnP mirrors you've worked with I'd be all ears (or where to buy either online!!) Let me know via PM or here.
Kinda sounds like the aftermarket is a PIA.