Hack the key fob. I have done it. My take is you only want to do a raise / lower for 2 solenoids right. That would be 2 channels. If you want more channels they come in 4 channel versions also. Additionally the ones I have used offer either latching (you click once and the relay latches, click again and it un-latches) or non-latching where the relay is closed only while the button is held down. Extending the key fob buttons was easy.Thanks Ron,
It needs to be controlled by fixed locations on the steering wheel. E.g., a set of paddles. The paddles could then be split into 4 with the bottom two being switchable to operate the remaining pumps.