Just a thought-but have you guys considered using a soft bag like Dirt Bike Gear Fender bags for the rear or even a Giant Loop Mojave bag?
If you're just looking to store tools or tubes etc a small bag fits on the rear fender really well. If you're looking to carry a bit more then the Mojave can store your gear and be removed. I've had a PMB rack and they really are nice, but if you want to carry something only occasionally, a soft bag might be another option.
Or even a small tank bag works well. I use the Giant Loop Fangango on my 500 and it works well. I don't find it's in the way.
I like bikes...