I wanted to say thanks again Bogo, I went with the Polymax board and 1/4" 4x8' shipped to my door was only $107! Cutting it was easy, but install was a "CENSOR" due to me over installing it (I'm a perfectionist), but good news is no one will ever steal my rack without multiple hours of work.

Here's some pics...
We wanted to help decrease the cabin temps a bit more and so we were told that the old Land Rovers had a double roof design that created a shaded area between the rack and the roof and thus creating lower cabin temps. So that in mind and with the help of some friends and such we bought UV stable marine poly board (much like cutting board). Here it is after it just arrived.