Best practices for attaching panels to roof rack cross bars?

Overland Vehicle Systems Freedom Roof Cross Bars for OEM Side t slot cross bars Aluminum length adjustable crossbar with t-slot channel available This t-slot channel give full availability to add bike rack or tent on the crossbar thunderstruck slot machine Home Go Rhino 5935015T - XRS Cross Bars Bed Rail Kit for FullMid Sized Trucks WTonneau Cover T-Tracks -6% T-Slot Cross Bar Close

timeless rose slot Yakima 8001161 T-Slot Mounted Load Stops for Yakima HD Heavy-duty Crossbars and other T-slot Bars are ideal for positioning and holding loads in place Load