You can mount an ELCAN with the RAS II Rail.
The ELCAN uses a close eye relief.I had an ELCAN mounted on my RAS II and had no problems, and the eye relief was good.
BTW, the RAS II was designed for the Aimpoint Comp M2.The RAS II "hump" letsthe Aimpoints red dot co-witness with the front sight.
I might have some pics around of the ELCAN on my old rig if needed.
SKBY.