How can I add side bars to my simple Rhino Rack?

I have a simple setup--Rhino rack HD cross bars with short risers on my rail mount tonneau. Serves its purpose as a bike rack carrier and anything that can span the bars and it has a QD functionality so i can remove for larger loads. But my issues is that there doesn't seem to be anyway to use the bed side areas with any kind of add on.

The typical taller racks all include some kind of side rail or panel that you can attach between tall risers other accessories. Since this has short risers, you cannot add a side bar between. I also cannot find any readily made solution from Rhino. Can't even find a bracket from them that would allow you to mount another set of HD bars length wise and turned outward on the existing cross bars.

Any ideas how to get some sort of universal side bar or panel running length wise? Was thinking i could cobble something together with 8020 extrusions but not sure how strong that stuff is.