What I did for the rack(similar issue) on mine was a couple nuts and a longer bolt. The nuts form enough of a standoff, not same size but larger bore, then the puts the arm out past the caliper widthwise but still in the same line it wanted to be. Make sure you use a good enough grade bolt that can take the leverage, but it shouldn't be a problem. My touring rack takes a lot of loads continuously and has never bent or broke the spaced mount.