Maximum eye relief is approximately 3.75" and this is TruGlo's description on re-indexing the turrets:
"After you have zeroed the point-of-aim of your scope to the point-of-impact, the turret caps will likely be in the
incorrect position (indexed to any number other than “0” ) and will need to be indexed correctly. To “slip the caps” back
to “0”, first make sure the turrets are in the locked position. Use the included torx wrench to loosen the screw on the
end of each turret cap. (It is not necessary to remove it completely, just enough for the cap to turn freely) Once the cap
can rotate freely, align the “0” mark to the indexing dot on the scope body. The turret should NOT click when rotated
(as the turret is in the locked position and only the external turret cap is moving). Re-tighten the screw on the cap to
hold the cap firmly in place. Do not over-tighten. Do not apply threadlocker to this screw.
With the scope and caps now properly adjusted, you will be able to dial additional adjustments (bullet-drop, wind,
spin-drift, etc.) into the optic as needed for a particular shot and then return the optic back to your predefined zero. "