First, educate the possible suspects. Let the kids know that if they touch those handles that terrible things will happen after you tell their parents.
Next, a label on the handles would not hurt like "Zombie Bio-Hazard - Do Not Touch" but I could see that back-firing.
Finally I keep the clear 45 degree elbow on the outlet so I can see if there has been a leak for whatever reason. If there is any sign of a leak, make sure the handles are all the way closed and get rubber gloves and a bucket. The pipe to the tank should not hold more that a gallon or so when the valve is closed.
2011 PrimeTime Tracer 2600rls
2001 GMC Yukon XL 2500, 6.0L 4.10:1 axle ratio
Nights camping 2014 - 17
2013 - 15