The Oscillator AM noise measurement may require some more thinking.
Here's what I tried that didn't work:
Lock the IFO in a bright michelson, lock the OMC to a 33MHz sideband. Change the modulation index, watch the DC level change. That worked. No AC excitations, however, could be seen in DTT. It may not be possible to drive it hard enough, which seems strange because this should be driving the error point of the RF AM stabilization loop. It could be that there just isn't enough signal to overcome the electronics noise in the photodetector.
Next easiest thing to try is to do the same measurement with a power-recycled michelson, and thus get a lot more light. This will almost certainly need to be done at night to minimize alignment fluctuations, which are large for the PRC.
In any case, a complete characterization of the RFAM black box is in order.