Lets say the refueler lives 10k or so from Airport.
He has to put on PPE, drive to airport, get the tuck out, deliver the fuel, complete paperwork, put the truck away, secure the yard, drive home. Not to mention the DAMP requirements for 0.0 BAC which effectively means if he / she is on call, they can never have a drink.
So an after hours overtime rate, $85.00 is pretty fair in my books. As long as he is giving you a tax invoice for it.
Charging multiple aircraft for the same callout is taking the pt1ss though.
Some airports are charging well over a hundred at the moment.