Remember my concerns last week on building a tow rig without a fuel plate.. and

worrying about a non-accustomed driver behind the wheel?

How about installing a valet switch... somewhere where I'm the only one that knows about it?

We had a 12 valve at work that we installing a battery switch under the seat to prevent the batteries to drain while sitting. You could do that

From what I understand of the valet switch system that is out for the 12v trucks it would probably limit the fuel to much for the use you want.

You can d it about any way you want. You could put in a solenoid and put the switch anywhere you want or you could plumb some tubing and put a valve in line and mount the valve where you want.