Do you have a disc compatible rear rack? I'd like to hear about it.

I've got a cyclocross bike that I want to put a rear rack on for commuting and light touring, and I'm having trouble selecting the right rack. My default choice is the Topeak Explorer with disc mounts. Can anyone with a Topeak disc mount rack tell me how much clearance the 'spacer pegs' at the end of the support stays provide? I have BB5 road discs, and it appears I need 2.5cm of outward clearance from the dropout/eyelet to clear the brake unit.

I've been looking into a couple racks that mount to the quick release skewer. The Axiom Streamliner Disc and the Tubus Disco. It appears that both of these racks provide 4cm of rearward 'swoop' to clear the disc unit - but it seems like I'll need 6.5cm to clear behind the unit, unless it's also spaced outward to some degree [caliper arm curves inward, lessening clearance distance if rack is spaced outward].

Any thoughts or suggestions appreciated.