Is my hose for overflow or winterizing?
Depending on your setup, yes it can be used to fill your fresh water tank. I use mine to fill my tank all the time.
You ask how? If you have an outside shower right by your fresh water tank fill connection, you can connect your outside shower hose (may need to take the shower head off and get an adapter) the put the anti-frees hose in your water jug as if you are winterizing your unit, turn the pimp on, then open your outdoor shower valve. The water will flow from just through system as if winterizing the outdoor shower then back through the tank fill and into the fresh water tank.
If a picture would help let me know and I can take some later today and post.
2013 F-350 Turbo Diesel
2016 Heritage Glen 368rlbh