Quiet's "cover me" command turns almost any mission into easy mode.
Hell, Quiet's "cover me" in general makes the game easy mode. You can do side-ops and just have her distract them to the point of you choking the hell out of the back-turned enemies. Only problem is vehicles, but well... you can stop those yourself.
I just researched Diamond Walker's mark mode, I should see how good that is in regards to marking the world.