For trips over 5 hours, I leave the LP on...under 5 hours, I turn it off and when we arrive 4+ hours later, everything in the refer/freezer is still cold...Just be sure the doors are closed tight while traveling. We have been doing this for 30 years and NEVER had a problem.
2008 Dodge Ram 4X4 Quad cab LB 2500 Cummins 6.7L TD / 2013 Columbus 320rs. Camped 50 days in 2015. RIP Angel the camping Cat, we will miss you.