I don't have 3rd row experience but I do have hauling experience. For a full 4x8 sheet to fit the rear door would need to remain open. One option is to use the roof rack basic carrier, a 250-300$ accessory. With the carrier on, 3 - 1x4's eight feet long will support 4x8 sheets well up to 200# and tied down well. Option two is a trailer.

Jim