We have an 07 Armada SE. No rear speakers. What's the difficulty in installing speakers for the 3rd row area? Are there any wireless options out there? Thanks.

wireless??

Welcome to CA dyw4ua!

jameeler did it.
http://www.clubarmada.com/forums/member.php?u=2296
http://www.clubarmada.com/forums/showthread.php?t=8962

And cheezmo1 did too, but on the liftgate!
Have you thought about the tailgate?
I installed 2 6.5" in the rear tailgate, similar to Qaher's:
http://www.clubarmada.com/forums/attachment.php?attachmentid=2742&d=1155148956

Mine's an 06. The 6x9's were just too big to get an exact fit because of the space needed.