Rear wall reflections from hanging objects

I know that in general that the back wall in a control room should be completely absorbent if the room is small to medium size. It’s also my understanding that as rooms get larger, hard surfaces in the back are OK. My head will be about 9’ absolute max from the back wall in mix position, so this will fall in the possible comb filter territory from what I’ve read. I’m going to be installing a mini-split AC system and the back wall would be the most convenient from a installation standpoint and an aesthetic standpoint inside. My control room is 11’ Wide and 16’ 6” from front to back. The internal part of the mini-split that I’m looking at is roughly 2’x2’ and 5” deep. Is the mini-split small enough to not worry about it so long as it’s not in line with a direct reflection point? Would just putting it on a different vertical plane then the speakers be enough? The rest of the rear wall will be 6-8” deep mineral wool or fiberglass with cloth.