...we have heard that they're understaffed and swamped these days.
Presumably swamped with stupid and obvious applications from Apple. Maybe if they asked nicely, Tim Cook would lend them a few dozen staff to rubber-stamp them all and cut out the middle-man.
I'd also wonder about the magnet strength required. As noted above iPads aren't light, so unless the magnets are stupidly strong, one pothole in the road (not that we ever have those in this country of course) and your iPad is suddenly heading toward the floor, the gearstick and/or your lap. No possible risk to you, those around you or the hardware itself from projectile pads, oh no.
And not to mention how distracting having such a large screen in the windscreen area would be, nor how much of your view it would potentially obscure. Using an (almost) 10 inch screen for a display of anything that close to a drivers field of view is just plain dangerous.
And as for using two together, so basically you take 2 iPads, a few magnets and make the whole lot into an oversized Nintendo DS? Where don't I sign up?