Have not had time to start on the pannier racks, but did do the redesign on the rear seat mount. Previously I had to remove the rear seat frame and undo the bolts from underneath. That was not going to cut it, especially when I want to EASILY be able to swap the seat for the top box mount.
This is a two step process. The first step is to make the seat quick detach, WITHOUT removing the pillion frame to do it. Mission accomplished. No pics just yet, am trying to video it, so it males sense, plus I probably need to redo the video.
Basically I made a tongue that goes under the cross bracket of the rear seat frame. The tongue is riveted to the seat bottom. Then to lock it in, I made a U shaped bracket with the ends beside each of the threaded 6mm holes in the pannier frame. This bracket is also riveted to the seat bottom. All are 5mm rivets. So to put the seat on, I set it on the frame, slide it forward, and align the two 6mm bolts on the sides and tighten the 6mm bolts. To remove the seat, remove the two bolts on the sides, and pull backwards amd lift. One bracket is 1/8" steel, the other is 12ga steel.
As mentioned, once I make a decent video I will post a link. It will be a lot easier to understand. The rear, larger holes on the back sides of the frame will be used for the pannier frames to mount.
Tomorrow, I hope to figure out how to mount the top box bracket to the rear seat frame, in a quick fashion as well, but also one that keeps it from being easily stolen. Mostly I want the mounting bolts only accessible when the box is removed.