I've been looking at different set-ups/ideas for the van for some time now. One consideration I have is the cab area being so big, I almost need to have two areas for mounting. When I'm alone, I want the devices closer to the driver's side and when my wife's with me, I want them on her side so she can handle navigation & comms (I know......Risky.....). Here's what I'm leaning towards:
Both Ram Mounts and YakAttack (kayaking accessories) make mounting rails for the round ball mounts. These are low profile and come in different lengths. For strength and to reduce vibration, I'm adding a backing plate on the underside of the dash, so the actual dash will be sandwiched between the mounting rail and the backing plate.
This system will allow me to easily slide the devices from left to right as needed. It will also allow me to keep them away from/above the airbags.