I still have a RAM 1000ES with the same box. The ignition is started from the start box, so, YES you must use it. The Start box also plus into the ECU to monitor/run the engine during start up. The propane is regulated by the start box, but I am sure there are ways around that, so read from that what you will. I am sure you can just plug in a battery to the starter motor and have it spool the engine (don't know if there would be any greater damage to your starter motor that way) and I am sure you can just plug a propane bottle directly to the engine, but that also leaves you with more external things to try to control.

Turbulence