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?
2003 DR 650.(1976 Montesa 250 Enduro-nice!) - - 1990 MASI TEAM-3V.- 1976 Motobecane, Super-Mirage.- Kona, HumuHumuNukuNukuApua'a. Single Speed ThRaShEr BiKe. 1968 360 Greeves challenger MXer. 1999 Triumph Trophy 1200. 2011 KTM530 EXC. 2012 KONA Hei Hei Deluxe (ongoing bike issues) -2009 KTM 200XC-W.