Kinda sucks that the SX-P trim wasn't really designed for a young family {of 5 or more) with 2 child seat in the VIP chairs plus a 3rd child in mind. The seats are unwieldy, clumsy and inflexible. More suited for a family of 4 or for ferrying the parents-in-law in style and comfort.
This has been my thought as well. It's a very cool package to offer, but I assume most minivan shoppers are thinking about car seats and strollers, and not luxurious captains chairs.
To the OP, I know it's too late now, but I always recommend taking your car seats to the dealership and testing them in the vehicle before you sign on the dotted line. As mentioned before, the middle isle is your easiest access path, but it's certainly not going to be easy. If you have a car seat that is also a carrier, have the passengers enter the vehicle from that side BEFORE you drop the carrier into the base. That might make it a little better for them.