Maybe this will help. Upper diagram is what he has now. Lower diagram is what could be done if you want more clearance underneath.
There are 3 potential mounting planes:
1.
@Joagmon 's nifty method is to create a new lengthwise rail (.75 or .5" tall) below the centerline of the factory side rails. (upper pic in my diagram)
2. The common method is to add cross rails at the centerline of the factory rails (not pictured in my diagram)
3. The potential
@gregnash method could be to flip the method 1 bracket over so that the new rail is placed ABOVE the factory centerline. (lower pic in my diagram)
Green : Factory side rail
Red: 8020 Bracket
Grey: Extrusion
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Yeah, I'll share my build when it's done.
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