It seems that the V-storm in the picture has the brake and directional lights on the saddlebags to solve that problem.
Would you consider turning the assembly 90 degrees clockwise over the horizontal topcase rack and making the pivot perpendicular?
The lever is small; hence, 20 pounds and aerodynamic drag off-center wouldn't cause much trouble.
http://golfscene.ca/wp-content/uploa...cle-_caddy.jpg
You could add some wheels and make it a caddy carrier.........
http://s7d2.scene7.com/is/image/GolfGalaxy/PAPMICINOLJPKHFK?$s7product$
.........or use some anti-theft bolts on the receiver tube and some lockable pin in order to remove just the rack when not in use.
http://www.specialized.com/aw/en/ftb...theft-bolt-kit