Jon,
The Pressure Pro Installation Manual FAQ page includes the following statement ref the use of equal:
"CAN I USE A SEALANT OR EQUALIZER POWDER IN THE TIRE WITH PRESSUREPRO? It’s recommended to use a filtered Dill Valve if using sealants or equalizing substances. Sealant can plug up the valve core and shut off pressures in stems."
When I purchased the system and asked the question about equal, I was told not to use either equal or internal tire sealants. I would suspect the sales folks were not aware of the existence of a filtered Dill Valve. Since the sensor is the only seal, I wouldn't feel comfortable with foreign material in the tire in any event.
The sensors screw on the inward facing valve stems easily and only require finger tightening. Remember that the lighter weight wheels used with 40 footers have large lightening holes. It may be necessary to rotate the valve stems on wheels with the smaller holes.