I'm running SKS Velo 65s.
VELO 65 MOUNTAIN - SKS-Germany
You install a little, L-shaped metal piece and the fenders just slide on. There are optional stays. I use the stay on the rear, but not the front. Coverage does not match my old, aluminum fenders, but I figure the trade offs are that I can run much wider tires and they should come off easily for packing.