Great idea by the OP, much easier than the big plate approach. One note for folks that plan to follow this route: steel + aluminum = galvanic couple... the aluminum is most likely going to corrode at the contact point with the steel clamp. A piece of thick lexan substituted for the aluminum would likely provide the same mounting strength but no corrosion risk.

The steel is chromate plated (that's what gives it the yellow tint), the aluminum is completely compatible, no need to worry about corrosion.

http://www.engineersedge.com/galvanic_capatability.htm