this is exactly what I did.I wonder how it would be to hard wire a phone line "power cable" from my Bell Pro 200 on my 2018 ST1?
my Radar detector is a Escort Max 360. Beltronic detectors are the lite version of Escort's so they use the same basic and smart power cords with the RJ45 (telephone) connector. but because of where I was mounting it right under the mirror and well within reach, I didn't need a separate mute button like the one on the Smart Cord. I just took a 12' standard phone cable and cut the RJ45 connector off of one end. I had to do a little testing to figure out which wire was which but it wasn't too hard with a DMM. two of the wires ended up being for power and ground, one of the other wires could be hooked to a switch for the mute wire and I was guessing the last wire was the feedback for the flashing light next to the Smart Cord's mute wire.
As long as that fuse 85 had Acc/Ign power, it would be fine