I made my own heated water hose, here's how I did it: Take an ordinary white water hose. Buy heat tape from the local hardware store. This is not "tape" but rather a strip of wiring that heats up in cold weather. I got a 30 ft heat tape for my 25 foot hose.
Using electrical tape, attach the heat tape the hose. You have to decide which end of the water hose you want the plug for the heat tape. Some people put it on the female end, because when you connect to the spigot, there is usually an outlet right there at most FHU sites.
After you tape the heat tape to the hose, wrap the hole thing in foam pipe insulation, also available at hardware stores. Then, finally, wrap the entire thing in duct tape. It will be stiff and somewhat harder to store than your normal hose, but it won't freeze.
Hopefully your RV park has their spigots insulated and heat tape wrapped as well.