I use rail ladder covers to bracket my QD mounts. Just cut to custom length and it is impossible to mount anything in the wrong spot. This is for QD red dots, magnifiers, LPVO, thermal scopes, etc. The only exceptions are if it is so far back it runs up to the BUIS, so far forward it runs into a switch, or two optics have overlapping mount points, like an LPVO and thermal scope... in which case I try to limit one optic (like a day optic) off the front and another more rear mounted optic that overlaps some of the day optic mount footprint but requires a couple more slots to the rear (like a thermal scope) off the rear.