You SHOULD vend air. I added it several years ago...mainly caused I was often asked. If I was on sight, I’d let them use the line in my E/R.
Now I have a line run from the E/R to a vac against the building. A KIP solenoid and a toggle switch allows customers to switch between vac or air using same timer. Just needs occasional cleaning of the screens for rust etc. I’ve got a good air nozzle with pressure guage built in. Works great...and it’s basically free $
I also have an F350 and a couple trailers and both call for 80 PSI. I am thinking of setting the air at around 85psi and hopefully that covers everything. I have been to gas stations that have air and I think the pressure is set to low and end up losing air when I try to add.
We were originally going to go with a fancy "real time" digital readout system but after seeing the logistical both short & long term cost we got cold feet. Has anyone gone that "wow" factor route without putting too much pressure on their bank account?