Adding the Euro LED DRL to an American 1200RS

[Pyrrho]

Would something like an EZCan work? Not cheap, but neither is the switchgear you'd need for Euro bike (I assume).

https://www.hexezcan.com/

Oh, that's probably what you meant by 3rd party controller....never mind.

Having just bought a Denali CANsmart controller (identical device to the EZcan except it comes with additional cabling), an EZcan is what I'd suggest investigating as well. Can auto adjust with high/low beams, flash w/horn, flash alternately with turn signals when hazard mode activated, selectable power output per circuit with built in selectable limiter, etc. They can be daisy chained to provide additional circuits as well.