KJ,
The Aperion manual shows suggested mounting of either side placement or rear placement as being acceptable.
If your receiver has both surround and rear surround you can also experiment with which sound you like best.
The L/R placement of the 534’s is up to you. I have mine configured so the Bi/Di switch behind the grill is easily accessible. You may want to place the speakers so the switch is pointed away from the couch on each side.
Once you get these things mounted you may not want to hassle with swapping positions since you are trying to line up the mounting slots blind. Make sure you are level with the anchors and the spacing is correct to within 1/16th inch or less. If the center for the anchor is correct but the angle is off you may not be able to engage both mounting slots.
Trust me, I know.
Jack