I don't have much experience with Field-IQ and would really like to keep it that way but I did play around with a work switch on a display stand last year.

At the moment, I am of the opinion that there are two different approaches that could be used with a work switch.  As I recall the switch that you refer to as P4 had a menu setting that needed to be activated. When this was activated the system watched for the switch, otherwise it did not pay any attention to the switch.  I'm thinking that when the switch settings was activated that you were presented with questions so that you or the system could determine whether you were using a "normally open" or "normally closed" arrangement.

I'm thinking with that arrangement, the Master switch and the work switch operate in a series arrangement.  That is the Master switch AND the work switch would both need to "ON" for application and coverage to occur.  This means that the operator could stop application by shutting the Master OFF or raising the rig.

I think that using the Raven Orange and Orange/white wires may be another option.  Those wires are wired in parallel with the Master switch.  That means that if either the Master switch OR the work switch completes the circuit that application would take place.  I don't think this requires any programming but has the disadvantage that the work switch would always activate application any time the rig is in the Down position.

Again do not put too much stock in the above comments since I haven't played with this much.