Hiding an infrared motion sensor.

Im not sure if this is the right place for this, perhaps but please remove if not!

Im building a Nixie tube clock and to preserve tube life I’m going to try and have the display only activate when the clock detects motion. I want to hide the sensor (one of these) in the case to keep the clock looking nice. As the sensor uses IR to to activate I was planning on hiding it behind a small circle of 650nm high pass filter.

In my head this all works fine - IR sensor works through the filter, visible light doesn’t meaning its hidden and looks smart but still functions. Would this work or is there a better way?