From the vault of "Answers to Questions Nobody Asked."
After much fiddling, I finally decided to mount my V1 just above the mirror using the visor clip/headliner trick. Here are the results:
The one drawback (the infernal dots) is obvious. I won't know how much of an impact they will have on LIDAR reception until I run through a few traps. Radar reception should be fine, though, because it does completely clear the top of the rear view mirror.
I tried a bunch of other options and nothing else worked all that well for me. My other cars have had the blue tint strip that did a good job of hiding the suction cups for a high windshield mount, but the Prius doesn't. That means that the suction cups are plainly obvious and I fear they would invite a break-in. (And we all know what happens when you continuously mount and unmount suction cups.)
I also tried the plexiglass trick to mount it just to the left of the mirror, but that was even worse than just suction cups since the mounting tape is white. I have some clear dual-lock strips but they put the plexiglass too far from the windshield for the V1 to be leveled properly. My one success here was the hard-wire. The wiring for the dome light is easily accessible and there's tons of room to stash excess wires above the headliner.
Works for me, at least until I change my mind.