This is really interesting! I would really like something in Carbon fiber in regards to side paniers. This isn't it, but it is a visual for something like it. I invision an aerodynamic disk shaped panier made from carbon fiber, loaded from the top, not exceeding the top plane of the rack, bolted on from the inside to prevent it being taken off the rack, and lockable. You might even use the bolts from the rack itself to bolt through the pannier, through the rack and into the brazeon. Strong material, lightweight, and waterproof. I have the Ortlieb Tour Box but it does stick out a bit more than I would like for commuting around town. I seem to get it caught on things too (telephone poles, retaining walls, fire hydrants). These panniers really don't need to be all that big (each) but together could provide enough room for a windbreaker/raincoat, extra tube, multi tool, headlamp, gps, lock and cable, and anything else you didn't want stolen when you lock up your bicycle. Besides, it still leaves room for a nice lock box on the top that I am still working on also.

https://www.velokraft.com/vk2-tailbox.html