I have basically finished my custom rooftop tent rack project (aside from the front air dam and auxiliary mounting stuff)... Below are the updated pics. Basically it has four ball detent fast pins that allow it to be locked in a few positions and it slides on needle bearing cam followers. This allows for easy mounting, removal, acting as a shade structure, or sliding forward to give you a little rear deck space for your shoes etc. outside the tent. Its also way lower to the truck than my old Thule rack set up. This is great for getting into parking lots with low overhead height, and makes for better overall aerodynamics.
closed and locked position
Attachment and fast pin detail
Slid back in shade mode
Slid forward in camping with deck mode