I've got a 99. All I can say is good luck with that.
My 12 and 14 year olds are uncomfortable sitting next to a Radian in the center and they're both pretty slender. It is TIGHT back there. I've yet to fit anything side by side that left room for another passenger, much less a seat. I think perhaps Radians on the sides and a MR or Britax convertible center so it could overlap the edges of the RNs, but I think that's about your only bet. MAYBE a literider on one side instead of a RN, but I don't know for sure and I don't have those seats or I'd try it for you.
Can you not put 2 kids in the 2nd row, leave the seat behind the passenger flipped down, and put two more in the 3rd row? That's what I'd do if I only had 4 kids.
By the time you have another, your oldest will be in a booster and you could put him/her in the flip down seat and still be able to slide the seat forward for 3rd row access.
I promise there is no vehicle short of a bigger van that seats 12-15 that will be easy to access the 3rd row in with 6 car seats. Sorry.