Like Fixit suggested but with only one relay that had 2 sets of contacts...common, n/o, and n/c.
One set to the starter solenoid and the other for door power interrupt.
Only one relay to mount and wire.
This is also a possibility, but finding a readily available 2PDT 12v/30a relay (not of the industrial control base/socket type - I.E. IDEC) isn't easy. You can get the Bosch "Ice Cubes" anywhere.