I changed my plumbing a bit to deal with freezing conditions outside. Since my fill line is no longer part of my distribution line, after filling I can completely drain the fill line so there's no water in it. I know that doesn't directly answer your question, but it's another added benefit of replumbing your system to separate the fill from the distro. The only negative is you can't hook up to a water hook up and use the water directly if parked for a long time.
Hmmm, wait a minute... I just reread your email... are you referring to the removable hose instead, not the main internal fill hose/line? Let us know...
2006 RB50 6.0 Diesel
Flatplate water heater (mounted INSIDE), portable butane stove (no propane)