Yeah, I’m happy with the 20in and the blendmount for my uniden r7. Looks and works great, thanks for the detailed post.Can you put up a link to that 20in? That'd be perfect.
I do remember trying behind the rear-view mirror, this was my first approach. There was a harness of sorts in there but I remember it being very tight. It probably carries enough current, but I spent a decent amount of time on it in general so then moved onto the dome light.
Lots of people have also ran a line all the way down to the passenger footwell fuse panel. There are plenty of slots, and apparently it's quite easy to tuck the cable into the body panels. For me tapping into that area seems like the best bet though. Good luck!
I found the 20in on amazon here:
MTX-1020, RJ-11, 20" Long Overall Length, Patented Radar Detector Power Cord with 2 Amp in-Line Fuse, Military Grade Taps, Made in USA https://smile.amazon.com/dp/B00L2SV...i_i_XA0VFZ5C5PG7WMFEXWZP?_encoding=UTF8&psc=1