Everyone's comfort level is different, of course, but I've not had any freezing problems with the following steps each fall. My 2009 Hawk has the pump, hot water heater, outside shower, and that clear plastic hose Ramblinman is asking about. I find it's easy to get all the water out of the system so that no anti-freeze is necessary. FWC gave me the basics of these instructions and they work well.
1. Drain the water tank and leave the drain valve open. (Leaving the valve open reduces the possibility of damage from any freezing drops of water in the drain line. This gets rid of any water in the tank that you wouldn't want to freeze.
2. Open the sink faucets (pump off) to relieve pressure in the lines and then go outside and drain the water heater by removing the drain plug. This drains the water in the tank that might otherwise freeze. Put the drain plug back in the water heater so the hot water lines can be blown out in the next step.
3. Connect the shower head, open the sprayer and both outside hot and cold faucets. Turn on the pump and run it until water no longer runs out of the shower head or the sink faucet. This clears out the pump and blows out the lines to the sink and shower.
4. Turn off the pump but leave the sink faucet on. It doesn't make much difference if you close the shower faucets or not because when you unplug the shower head the camper half of the fixture seals the water line.
5. Open the valve to the clear plastic hose and drain out any water remaining there at the bottom of the system.
That should do it. You might want to drain the waste water P-trap under the sink, but I always forget and haven't ever had a problem.
One nice feature of the water system is that my Hawk came with an extra valve located below the pump which closes off water from getting into the water heater and the hot water lines. This is a great advantage for people who want to use the system for cold water during winter camping but don't want the hassle of blowing out the hot water system when the excursion is finished.