It takes a while to heat up the 6 or so gallons in the heater. The thermostat should shut it off when it reaches temp, and it has a relief valve which should open up before it would explode. Leave the pilot light on or you will have to keep re lighting it every time you want hot water.
Model X19H Expandable
GMC Sierra Pick up
Been a camper since I was a kid, and that was a long time ago :)
From pup tents with no floors, to tents with floors and flies, to a pop up, to the expandable.