The main problem with putting any kind of filter before the pressure switch is, if the filter clogs up, the pressure switch can’t shut off the pump, and you burn up the motor. I think the filter maybe less likely to clog up than the pipe after the air charger. Either way the pressure switch will not be able to shut off the pump. Sometimes you have to do this to make the system work. So put a 75 to 100 PSI pressure relief valve prior to any filter. It will pop off if the filter or pipe clog and save the motor.