First things first: that is a pretty cool set-up.
Unfortunately, as I found out earlier this year, it's also absolutely illegal in AZ. I wasn't shooting from my vehicle; I'm just saying 'unfortunately,' because I think that's a neat idea.
However, the game and fish officer I spoke to in March said that shooting from a vehicle
for the purposes of hunting, at all is illegal, and that earlier that day he had to cite some guys that had a 'turret' style set up in the back of their pick-up. He said it was most impressive prairie dog shooting set-up he'd ever seen, allowing the shooter to rotate 360 degrees and allowed for elevation/declination. But because it was in the back of the pick-up it was illegal; if it had been on the ground it would've been okay.
Which is why I use a set-up like this, when possible:
However, if you're shooting at one of the designated desert shooting areas, such as the one off Table Mesa Rd., i.e., target shooting, then something like that is apparently legal. I see people shooting from their unmodified tailgates or over their hoods, or prone from their pick-up beds in front of park rangers/sheriffs' deputies all the time without repercussion.