It's tough
We're a single plane single pilot part 91 corporate operation. Unlike many single pilot single aircraft corporate flight departments, in addition to flying the Boss, I also fly a wide variety of other members of the company.
I've run into issues of being asked to depart at 0600 after returning at 2200 or 2300 the night before. I've ended up being able to educate the scheduler as to my need to get rest between flights.
Basically we've established an understanding that flight's should be scheduled to allow me a minimum of 10 hours away from the airport over night between flight, with day time down time away from home base to be used as I see necessary to get rest.
We're actually in the process of writing that very thing into our Ops Manual.
So far it's working out.