How did you mount that? any other pics?
That a 4 section Marine treated  3/4 plywood , seal and cover by marine Lacquer  ,made to open in life flow hinges (similarly to  parabolic antenna ) .So i put section on top of the car ruff rails( platforms Heavy but very durable and stable ) ,open them and secure to the  rails ,  and after simple put tent on top (if I will be expect heavy wind i will  tight nets to side  brackets for better hold .
The same part of the platform i use to cross a stone formation or when stuck on send or mud / i put them under a tire and go free :smiley_drive:     \
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Here a more photos 
http://s953.photobucket.com/albums/ae15/mamontof/My%20Travel%20Tahoe%202000/?start=80\
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