I made these brackets from sheet mild steel and bent them to form over the bulge where the shock mount comes through to the inside of the frame. I welded them on using a wire-feed MIG welder.
I used a heavier steel plate for the end pieces on the angle cut. I welded the end pieces all the way around then sanded out my welds. The end pieces close the rectangular section and significantly improve rigidity.
The brackets indicated by red arrows are for attaching an under-tail cover to hide the battery, electronics and hoses.
The green arrows are tabs that I will use to hold the brake light to the frame. The brake light will be slipped over the ends of the frame. This provides some support as well. I haven't quite figured out the whole brake light support issue just yet. I'm really trying to get all the welds taken care of before I powdercoat so I don't have to ruin the finish later on.
I also shortened the cross brace so it would sit lower between the frame. The stock fitting of the cross piece sticks up quite a bit and leaves an unsightly gap between frame and seat. This is usually covered up by the frame covers but I'm removing them, so I'm dropping the seat a little bit. After cutting the cross piece off the frame, I ground it down so it was a little skinnier. I then welded it back to the frame. I had to lay a bead down on the frame then set the cross-piece on this, then do a second weld on the top, and a third weld underneath.
My bike was missing the seat latch piece, cable and key assembly to release the seat. You can see the outline of where the seat latch used to be in the above photo. I ordered these new OEM parts from Suzuki of Oakland.That reminds me that I don't have a place to mount the key/lock assembly to the frame... Wonder where this is on the stock setup. I'll have to consult the fiche.