I guess I see it like this:
Anytime you see a dynograph posted on the net with afr line included, most were done so via a probe in the tailpipe. Are all of those cars catless? And if not, why does everyone seemingly love to scrutinize afr if those sensing methods were deemed bogus to begin with?
Mount it where I suggested, get a feel for it's normal readings and response, and go from there. You may not see "ideal", but after using it a bit you should be able detect "abnormal", and that's all a gauge is really good for anyways (if you even happen to see it when your foot goes down).
Fine-tuning, logging/detecting slight differences between banks is way beyond your intended goal, you will never accomplish that with a single gauge.
