Airlines have C & T with about 4 checks a year (2 sim and 2 on-line) why should passenger charter be any different (whatever the aircraft size). You are either carrying people for hire or reward or not. I have never understood the difference in the value of a human life between buying a seat (RPT) or renting the whole aircraft (Charter).
As far as private owners are concerned the youtube video of the citation swimming around a river on one engine is proof they need some sort of supervision.
has virtually excluded the Mustang from Charter operations through prohibitive costs.
So you are saying that 4 non-revenue flights on this aircraft a year will make it too expensive to operate?
If this is the case it was never competetive anyway.