PC mic source reference level for third-party clients - what SC_MIC level drives full SSB modulation

I'm working with a third-party SmartSDR client on Linux and
trying to understand the expected audio reference level for
the PC mic path (remote_audio_tx).

Empirically I've found that SC_MIC (meter 26) needs to peak
around -3 to -5 dBFS with mic_level=100 to reach rated PEP
on SSB. At SC_MIC around -12 dBFS (which appears as a nominal
level in some documentation) I only reach about 75-80% of
rated power.

A few specific questions for anyone who knows the firmware
signal path:

1. Is there a documented target level for PC audio arriving
   at SC_MIC that produces full modulation depth without
   triggering the SW ALC? Or is the expectation that
   mic_level gain compensates for whatever the client sends?
2. Does SmartSDR's PC mic path apply any internal gain or
   normalization before sending the VITA-49 stream, beyond
   the raw int16-to-float32 (divide by 32768) conversion?
   In other words, does SmartSDR send a hotter signal than
   raw 0 dBFS = 1.0 float, or does it rely on mic_level
   to do the scaling?
3. The ALC meter (post-SW-ALC) shows -6 to -9 dB of gain
   reduction during normal speech at these levels. Is that
   a reasonable operating point, or does it indicate the
   input is too hot?

Context: building a client-side TX DSP chain (compressor,
EQ, limiter) and need to know the correct output level
target so the chain's ceiling and trim settings are
calibrated to the radio's expectations rather than found
by trial and error.

Radio: Aurora AU-520, firmware 4.1.5.

Thanks for any insight.