Drill a vent/purge hole in my propane line?

"Drill" a hole in the line? Nope. I can't see a safety concern with a properly installed capped tee in the propane line but would it really help and maybe there's an easier method. You'd want a drain tee at a low point in the line at the farthest end under the RV and may already have a joint where it could easily be added. If you don't know how to work with propane stuff, get a professional to do it. You couldn't have a leg hanging down somewhere that could get hit tho.

Hank MI wrote:
What Chris suggests is the correct way. After opening and draining the lines install the drip leg. It will catch any water or oil in the future. Home natural gas lines normally or should have a drip leg installed. Should work the same for propane.

The gas line in our house has a drip leg hanging down about 3" at a low point in the house just before it heads out to the first appliance. I doubt it will ever get used but is a code requirement.