And regarding "For gain, I had planned to perhaps boost the gain at this stage and allow the later range adjustment stage work lower."
Putting all your gain up front generally produces lower overall noise; So if you are trying to make the overall system noisier, then use lower gain up front.
If there is a log-amp in between then adding gain after the log amp is fairly pointless, consider a random log-amp example:
Vin 1mV-> 600mV out and Vin 10mV-> 800mV out and 100mV -> 1000mV out and 1000mV in -> 1200mV out
So the changing the first stage gain by a factor of 10 changes the output by ~ 20%.
Note that the log amp will also produce intermodulation, so for example if you have a 20kHz carrier with some signal modulation, then the extra noise you add will appear as noise on your signal (and on the carrier), but maybe that's the effect you were after in the first place.