Problem Solved: space for the Arkel pannier connectors at the rear of the rack

Update. I've had the Arkel Pannier for two years. I just figured out that the clamps/locks are adjustable laterally. You can move them forwards and backwards, so the rack is no problem. D'oh!

I have to push that rear connector to get it on each time. I got a Breezer waterproof pannier for my laptop, and it doesn't have the same problem. Then again, the connectors on the Breezer pannier aren't that nice, but they are redundant.