Thanks for the info, John. I hadn't asked Gary about whether or not he needed felt or had any issues with scratching, so you're the first to report back on that particular aspect. Do you remember what tint brand/name you got? No biggie if not; I trust a good tint place to pick a good tint, given my criterion.
I had a feeling our factory tint was that dark (20% light transmittance). Actually, it's probably even darker, since the front windows are slightly tinted from the factory and if you have a perfect match with add'l tint applied to those windows, that means the rear windows and liftgate window are probably more like 13% light transmittance.
I'm going to stay legal, just because I know the local PD in my area and they've been known to stop for all sorts of things... although they certainly don't stop for burned out headlights 'cuz I see at least five vehicles every evening with a headlight burned out.
I'm going to set up an appointment in the next 2-3 weeks and I'll post a follow-up when that's done.