I have some Watershed drybags that I really love that I want to figure out the best way to use as bicycle panniers, does anyone have suggestions?

This is the model: https://www.drybags.com/product/assault-pack/

The backpack straps are removable and the bag rolls down quite a bit like most rolltops do. I think the loops where the waist strap is fed through may be a good attachment point but part of me thinks I'd need almost need side baskets or netting or a harness on either side of the rear rack that could just accept a a large bag without the bag itself having any great attachment points.