Tubus also makes an adapter that attaches to the QR wheel axle and provides an attachment point for regular racks (either Tubus or from other makers):
Tubus Quick Release Adapter

Vinyl-coated clips are frequently used to provide the top attachment points, but they can also be used on the lower part of the seat stays for the lower attachment. But unlike the above adapter, they don't move the attachment point back behind the rear axle and may result in heel-overlap issues on bikes with short chain stays.