Does anyone know of a rear rack that doesn't try to crowd the seat? I'm looking for one that doesn't try to put the center support bracket vertically over the axle, but leans back somewhat while remaining horizontal. So that there's a few inches clearance between the front of the rack and the back of the seat, in other words.

I use my bike for transportation, including shopping, and have a Topeak rear rack and basket installed. But they crowd the seat to the point that they interfere with seat adjustment. And since the rack has three support brackets forming 2 triangles, with all points of contact being welded, I can't think of any way to modify it.