Don't get me wrong, it may work, but if the pilot is awake and able it amounts to suicide.
I bet that I could do it with a Incubus or a Ice Ferret.
I got from the gameplay footage that the Atlas torso twist seems slower then the torso twist on the Hunchback. The same would apply to the Stone Rhino. The jumpjets wouldn't allow you to turn in a 180° circle like in MW2, a Ice ferret would be able to keep up with a jumping mech if it tried to jump forward while torso twisting to get a shot in.
I have already managed to stay behind far more manouverable mechs in MW4 (Cougar).
The gauss rifles are in the torso, it won't be all that easy to aim them with the current system for MWO.
The biggest threat are the pulse lasers, those things are fast and accurate, but trashing a LT or RT would diminish that threat.