Turbo 182: correct mixture for final approach at high altitude?

We took a newer 182 turbo to a 7000' elevation airport yesterday and
the engine quit at the end of the landing roll. I'm sure the mixture
was way too rich. It restarted without incident, glad we were on the
ground! We had the mixture set about 100 deg rich of peak TIT for
cruise at 9500. How should we have found the correct mixture setting
for power-off final approach, when the turbo is basically adding no
boost and we are at high density altitude? This is not addressed in
the POH. It does say full rich on takoff regardless of airport
elevation. Later that day, when taxiing for takoff, we set 1200 rpm
and leaned for peak rpm, mixture knob was out 1.5-2 inches to achieve
this.

When we returned home to 800' elevation, we checked the idle speed at
full rich, it was about 500 rpm, is this too low?


Thanks,
Barry