I have seen a few around with the dimmer switch in this location, my interior lights are controlled via the infotainment system.
It's quite possible that I had seen a post you made Cuzoe, it was a location I had considered. I set my amp up with an oscilloscope to ensure no clipping, I just wanted the bass knob for days when I don't want as much boom (I only have a single 8" so it's not that loud to begin with).
Same for your post StealthGTI, I had definitely seen yours, although I have the electric handbrake so no such location available for me. I purchased a spare trim piece to drill a hole in so if I ever want to go back to stock I can. From memory StealthGTI you had a pretty substantial audio setup in your trunk?