Don't agree with the answer from Suspended User.  But he has a lot of good answers on this site.  

I would not use the unit for compression.  I suggest:

 1. Remove unit 
 2. Loosen pinch bolts
 3. Use the bolt (shown in video) to put proper tension on headset
    bearings 
 4. Tighten pinch bolts 
 5. Re-install GPS unit

Mainly I suggest you start with a seat tube based unit.  Headset is a lot of fabrication.