decorative rod hardware help

I am going to mount some decorative rods for my soon to be made simple valances. the question regards clearance. I have 2" wood blinds mounted on the window frames, (old house). from wall to end of wood blinds hardware is almost 4 inches. the clearance for decorative rods is 3 1/4 inch. what do I do? put a piece of wood or ? on the wall and mount the hardware to that? and when I measure for the decorative rod do I measure the window, casing included and add 2 inches?