I wonder what his reason for the hidden compartments is. Seems to me that secreting away weapons in a vehicle, besides the prospect of a theft, is somewhat nefarious.
That said, I've transported my handguns in my pick-up many times but always under the passenger seat to comply with the 'out of reach' law. Building secret compartments for firearms could be construed as to facilitate smuggling.
If this goes to court it will be an intresting case.