Also I wonder if your master valve is leaking?
Cylinder internal leaking would be best under load,--BUT with it extended fully and up against relief pressure with gauges hooked up and watch how fast it drops could tell a little.
IF you had a simple stand to set the cylinder in then hooked under the rv that would work to hold it from tipping.

"A machine you build yourself is a vote for a different way of life. There are things you have to earn with your hands."