So with respect to radar, here's the things that we see cause issues with radar detectors and what works fine. The U3000's radar also operates on K band so the exact same principles apply here.
Good:
-Most windshields
-Non-metallic tints including ceramic tints
Bad:
-Heated windshields
-Some thermal/acoustic insulated glass
-Metallic-based tint
A common factor here is metal because metal blocks radar. It's also an issue we see with installing radar detectors in your grill. You want to avoid installing behind anything metal or even metallic paint.
As far as the rear heating strips, they're super thin so I'd be a little surprised to see it make a huge issue, but to be fair the rear cam's radar module is right up against the rear window (not up on the front window like a radar detector) and so if the alignment is just right, perhaps one of the lines runs right through the radar transmitter or receiver so it could be possible.
Certain higher end luxury vehicles to have heated windshields (which I believe also have teeny metallic strips running through them) or different types of acoustically insulated glass that could cause issues for radio waves. If this is the case, there's usually 1-2 cutouts on the window, perhaps near the RVM or the bottom center of the window, where you can place a toll pass, GPS receiver, or phone. These are areas with little cutouts designed to let radio waves pass through unimpeded. I don't think I've ever seen similar cutouts for rear windows since people don't stick toll passes or phones back there.