The eyebox is going to be quite a bit more fussy about head position than a RDS, as you already know. As long as your mount is the proper height, all you need is practice. The Vortex Razor Gen 2 has just about the most forgiving eyebox I've ever seen.
If you get that astigmatism corrected, Aimpoint or Trijicon MRO are the leave-on options you are looking for.