The biggest problem I have found is that my Kenwood KCA-RC700 steering remote now needs my hand to bounce the signal off and my Pioneer CD-SR80 won't work at all. May have to scrape some of the black from covering the IR sensor.

Or better yet, just re-print the sheet with a white (clear) "hole" over the IR sensor.

Unless somehow the sheet plastic itself is IR-opaque, in which case cutting a hole is the only solution.