Budget optic for a .22, designed to emulate a longe range optic... easy - Bushnell match pro.
Also consider some of the athlon options like the midas tac. Pay attention to how close the parallax goes if your shooting .22 close
A large frame AR dosent need a one piece cantilevered mount. I use seekins rings on my AR in 308 with the same DMR2 scope. My small frame ARs in 5.55 and 6.5g all use a one piece cantilevered mount. Geissele, badger, seekins, DD, admount.