A good reference is the BLS rates for "reasonable compensation" for that type of business in that region. Another metric will be the amount of wages relative to distributions. If the IRS were to come looking, and distributions are multiples of that person's payroll, they would likely determine the person's wages are too low for the specifics of that business.

I have watched webinars from:

https://rcreports.com/

And found them very succinct and helpful.