Howdy,I had a rear rack much like yours on my DRZe,using the seat mount bolts as supports and the one leg support underneath,,it never would stay tight and eventually broke both seat mount lugs off the frame. Kinda seemed like those little seat mount bolts were too small for the smaller rack I had mounted to them. I only had a medium size tool pack on it,maybe a 6 lb load. I guess there's no problem like that with yours?
Some bikes around at times