1723 Monitor Placement: SBIR, wall clearance, and surface reflections

Another dilemma I’m having with my room design is combatting SBIR nulls. My design currently calls for 1723 S Monitors to be placed on top of 1723 1V Subwoofers due to space constraints. The rears of the cabinets are about 13″ from the wall when I align the front of the monitors to the front of the subs, and I can see that creating an SBIR null issue. Typical advice to combat this is to place the speaker as close as possible to the rear wall to push any SBIR nulls into the high frequencies where they are more easily managed. Issue with that is twofold: one is Arendal’s recommendation that the rears of the cabinets be no closer than 8″ to the rear wall (either ported or sealed, or else the sound could get ‘muddy’), and two is I generally hear that if you’re going to place a speaker on a shelf then the front baffle should be aligned to the front edge of the shelf so you don’t get surface reflections. Regarding the reflections, is that only a concern for horizontally oriented center channel speakers or does that apply to bookshelves and monitors as well? If so, would a height boost from an IsoAcoustics Aperta platform help negate that if I were to place the monitor on the rear of the sub instead of the front? That aside, what’s the closest anybody’s placed a monitor to a wall without having any issues, and does sealing the ports minimize that effect?