A few years back I mounted a scope that was about that close. It had a relief cut in the center of the pic rail similar to yours. I sweated it for a while but never saw any signs of rubbing on the bottom of the objective bell. However, that was a Ruger bolt-action Scout Rifle with a barrel-mounted rail so there probably wasn't as much flex as you might anticipate on a floating AR handguard, particularly if you intend to run a bipod out at the end along with any other weighty accessories. A sunshade might complicate matters further.
It looks to me like you'll probably be OK, as the angle of your shot makes it appear that the scope is closer than it actually is, but without being able to hold your rifle in my own two hands and examine it closely I really can't say any of that with a high degree of confidence. Hopefully some of the experienced AR guys will chime in with some advice here, and maybe offer a minimum clearance measurement for you to use.