I use the heater cable. I have two 25' cables so that I can wrap the spigot and the entry into the 5'er. The cable does not get hot, it just keeps the hose around 40 degrees. It has a thremostat on and was about $25 at Wal-Mart.
I only camp for a weekend and the most a full week, so I can't tell you about long term. But it works great for me. I have used it it temps in the high teens with no problems.
2011 F-350 Super Duty SRW Diesel Crew Cab
2000 Sunnybrook Mobile Scout 27RKF
I use flexible pipe insulation from the hardware store and wrap it around the hose with tape to hold it in place. Water ran fine even with night temps in the teens for several days and shade during the day time. Cost me about $5 tops.
First law of science: don't spit into the wind.
Keep on rollin'!
A dripping faucet could over night overfill your tanks. Want to chance it? What would your Green Friends have to say about the waste of resource? Even with an open gray water valve if it is cold enough the slow trickle will freeze your drain hose then fill tanks and flood your rig. It is easy & inexpensive to make an heated insulated hose. Be the envy of your frozen neighbors.