Dmax is easy....take the tow hooks out and get some 3"x3" square tube (I used 1/4" wall) and cut enough tube away to where it slides right under the round cross member that goes through the frame. Mine go in like 4 or 5" with about 2" cut down to clear the tube.
If you come straight out, you'll have issues with the weights dragging the ground and the scales, etc. I miter cut mine into 2 pcs which angle up to keep the weights up.
Of course pay attention to the weights you use and design it so that the forwardmost part of the weight is at 60" from the axle centerline (or a hair less, to keep the tech inspector happy).