Guys, I have rigged an exact system like this for use in my next install, however, I am heading in a different direction now so I may not use it afterall. I took the slide switch out of an old Signalmaster box, soldered on a 4 wire trailer wiring harness, one lead for power then the other three leads to the switch position contacts to get the 3 position switching (this made the slide and wiring a "plug and play" type of thing). I rigged up a set of three relays with 1 amp diodes soldered across the 85 trigger poles so the power will flow to each relay from the previous one giving you the progressive switching that you would have with a normal slide switch while not feeding the coils from the opposite direction. The relays and diodes are necessary because the contacts on the slide switch are only activated in a singular fashion when the slide is clicked into each position. It's really simple to do, it just takes a little time and soldering. I have to give credit where it's due though. Sean Barr, aka EVModules, helped me figure out the relay/diode thing. I can draw out the idea and post it if y'all are serious about giving it a shot.