For those of you who are shooting reflex sights such as a Trijicon RMR or Leupold Delta point, how do you line up the dot for your shot?

I have had a Delta Point for several years but have never really been accurate with it. The trouble I have is that unlike my Ultradot tube sights, if my head is in a slightly different position with respect to the gun when I line up the shot, my shot is off target (parallax error). I guess the issue is that there is only one reference point (the dot) and positioning everything exactly the same every time has been a struggle, especially when distances start getting longer. The issue is not my shooting as with irons or with a tube type red dot I am good unsupported to 50 and off the bags, out to 100yds.

I feel like the reflex sights would work much better if there was a rear sight or peep type rear aperture such as a One Ragged Hole or the ones that Sixshot makes.

So those of you that use them, what is your secret?