I got my Solo Rack mounted today. I have a trunk on order... but it is hard to beat a milk crate for utility (and unique style).
I was not keen on mounting the rack directly in contact with the plastic of the handles. It is my opinion that, over time, the metal of the rack would "mush" and deform the plastic and everything could loosen up due to the slack this would create. I also wasn't keen on the idea of swapping bolts every time I wanted to remove the solo rack (longer bolts for shorter and vice versa).
So I decided to make a "hard point" for mounting the rack. I did this by turning 4 bushings out of aluminum. They are 21mm in diameter and ~18mm in length. The inside is threaded 8 X 1.25. (I used stainless threaded inserts for long life) (BLUE piece below)
I installed 8 X 1.25 X 45mm long setscrews (RED piece below) into the bottom half of the bushing using red Loctite 262 with primer. After this has cured, install them in place of the original bolt used on the grab handles. Use a Allen Key to engage the top of the captured setscrew and tighten it up very firmly. A touch of Loctite 222MS will ensure that this "Hard Point" will not back out as you install and remove the Solo Rack.
Now I have a hard, threaded mounting point for Ken's Solo Rack. I can install and remove the rack still with just 4 bolts (PINK and GREEN pieces below) , but I don't have to swap bolts and the grab handles stay put.
http://farm4.static.flickr.com/3628/3400911287_75a8aed31c.jpg
http://farm4.static.flickr.com/3660/3399414087_daa6da8670.jpg
http://farm4.static.flickr.com/3615/3400627830_3137be419d.jpg