I tried to pop it out every which way and it didn't budge.  That's why the hole I drilled for the cable is in that upper corner as I had no idea what was under the tray but could feel that corner from the inside when I removed the Instrument Cluster Panel. 

I have a different twist on your idea. I have a tom tom 730 with the slightly larger than average screen. I found a special order bracket to mount it directly on the dash behind the steering wheel. The location is where you would normally find the spedo in most cars so it looks right to me. I also like that since its mounted low you dont have the easy to see and easy to steal problem. I have layed a paper on the dash to cover it for more security. The cord drops in the crack over the steering wheel and to make it simple I put an extra lighter socket under the dash to get rid of the cords. I can unplug it and use the other bracket if i want to use it in another car. I later added the dash mat, carpet, and it was easy to cut a hole to stick the bracket thru and to me it looks great. The other bonus is that I still have a pocket for some small items.