hello rigustafson,
I would recommend you to use one of the following VGA with AGC detector below which are suitable for your applications:
AD8367 - 500 MHz, Linear-in-dB VGA with AGC Detector.
It can operate as AGC amp, in 6MHz range. Sample AGC operation with 0.354Vrms (1Vpp) set point is already describe on its datasheet. But you should take note on the impedance matching on your circuit for more stable operation of the part.
You can also try to use AD8368 or ADL5336 which you can configure your desired setpoint
AD8368 - 800 MHz, Linear-in-dB VGA with AGC Detector.
ADL5336 - Cascadable IF VGAs with Programmable RMS Detectors.
regards,
ahbie