Blue Cat's DP Meter Pro would be a good prescription for this type of issue. The product has everything you need for viewing and measuring RMS values. It provides the ability to adjust the RMS time period as well.
Of course it has the standard VU, Peak, and Crest meters, K-System settings, etc.. - and it can output many of its measurements as automation data.
Er, uh, and you can get it from the Cakewalk store...