I wondered about that other box's clearance. The tolerances are fairly close. On mine, I've cut the corner off to add room for the brake bleeder. It's worth watching to make sure it clears, but mine is working fine. I rode 2600 miles on the Continental Divide Route last summer and the box is still attached as solid as when it started. For mounting the top, I'm using a 1/2" conduit clamp (painted black on this installation) attached with a 1/4" stainless steel bolt with a flat washer and nyloc nut inside the box. The bolt goes through the box edge that's double thickness and so far, seems to be holding up just fine. Lower mounts have changed a bit, instead of 2 separate tabs on the box, I have started using one full width piece that's incorporated into the box and riveted on the bottom with L brackets and on the face with all the rivets in the lower part of the hinge as well (see post #31 pic).
Here you can see the area given up for the brake bleeder clearance.
Tolerances for clearance to the crud catcher are close too, although usually the crud catcher will shear it's own mounting bolts and fall off with sustained bumpy riding, so I just removed it.