For anyone in the future that wants to know how this turned out:
I ordered a Curt brand non-powered 3 wire to 2 wire converter. I connected the wires, gave it a test.... and it did not work. I should have read closer to the description that the converter I bought would not work for LED applications.
So then I went to the local automotive store and got this Reese converter:
Reese Towpower | 8507900 | Taillight Converter
That worked!
So in case anyone runs into an aftermarket rear light situation where the signals and brake share wires, use a trailer converter!
Thanks, as always, for your help guys!