I also looked into doing this, then opted for a double din dash conversion. However I was nosy when I removed the single din dash, I would say there is about 3/4" maybe up to 1" of clearance between the underside of the dash top (where there is what appears to be a removable panel) and the heater duct that provides air to the centre vent.
If you needed more then you would be able to heat and reform the air duct into a flatter shape, it would only give a little, but could make the difference between what you are thinking of fitting in there fitting or not.
The panel is NOT REMOVABLE, it is simply a decorative moulding line, but as Steve B as pointed out it could be easily and neatly (if you have a stead hand) cut out with a dremmel, if you are going to cut it out I would think about leaving the front edge uncut and using this as the hinge, as there will not be much movement the plastic will stand a lot of flexing before it starts to crack.
I was thinking of a design where the front of the 'panel' would lift up about 1" total, enough to allow a tablet to slide out and then rotate upwards through 90Deg (kind of like the single din head units with the 7" TFT screen do)
I do think it is doable, but there is a lot of work to make it look respectable, hence I went for the 2din dash solution and a head unit that had Satnav and lots of other nice features, I posted some pictured of it a couple of weeks ago in the in car entertainment forum on here
Best of luck if you do attempt it, and please post some pictures of the work in progress (I do like these types of mods)
Cheers,
