Air Gizmos GPS panel mounts

We've recently purchased one of the Air Gizmos mounts for our Garmin
296. I've seen it installed in another Cessna and spoken with the owner
who says no field approval is needed for this product. Our A&P, who is
a stickler for the rules(and rightly so if you ask me), says this
product requires a field approval as it is permanently fixed to the
aircraft. The reasoning the Cessna owner with it installed gave for not
needing the approval was that it can be disconnected and removed
easily. I assume he was talking about the actual GPS unit AND the
dock. I dont see how it's possible to install the dock and have it
easily removable, but hey what the heck.
The manufacturer states on their site, http://www.airgizmos.com, that a
field approval is needed for installation in a certified aircraft.
Am I correct in assuming then that a field approval is needed for this
in our Cessna? I dont suppose there are any ways around this for a
certified aircraft(non-experimental)?

Also, for those A&P's out there, just exactly what is the process and
all the hoops you have to jump through to get a field approval for
something like this. Is it documented somewhere where I can take a look
at it?
Our A&P said the first thing he'd have to prove to the FSDO what that
the product was fire-retardant. We've already contacted the maker of
the product and he sent us a pdf containing information on the plastic
that was used. He's also very interested in how our approval process
goes.

Thanks for any and all feedback.

Brock Boss
Student Pilot: 16 Hours
Co-owner: '67 172H