FWIW, I think the problem is people saying "move it straight down", or "towards the front". This is relative to the position of the tunnel as you work on it.
Correctly, you should draw a straight line from frt to mid holes, then work perpendicular from that for the 1.5" and .10" dims. I used to be in CAD, too.
Hmm, is this more of a "looks" mod, or actually effective in deep powder? How much are the brackets?