I hate even coming close to agreeing with Mr. Horse Stroker, but I think by putting anything other than a RMR up there you're flirting with danger.
Ive done my fair share of drilling and taping 6061 T6 aluminum and even though its Rockwell is better than what most would believe, its tensile strength sucks.
I have Permatex Ultra-Black between the receiver and the Scalarworks mount AND between the RMR to the Scalarworks. Wiped clean with a few Q-tips afterwards and you cant tell its even there.