In order to winterize with the "pink stuff" antifreeze, you need to pump the "pink stuff" from the on-board water pump, definitely NOT through your fresh water tank.
If you attempt to do it through your fresh water tank, you'll need about 10 gallons, and it will then be diluted with a bit of water from the fresh tank that never drains, and then you'll never be able to drain the "pink" from the tank either. No, you don't do it that way.
You pump the pink at the on-board water pump.
The first step is to by-pass the water heater, other wise, you'll need to pump 6 gallons in the heater. So by-pass the water heater, (drain it of course too), and then pump the pink at the water pump.
Depending upon which water pump you have and what was previously installed, you may already have the winterizing hose or may not. If not, you'll need to find a way to attach a hose to the IN side of the water pump. If your pump already has it installed, you just flip the valve at the pump and put the winterizing hose into the gallon jug of pink stuff. You then turn your water pump on. It will suck the pink from the jug and reach pressure level quicly. Then you simply go to each faucet and turn it on till pink stuff comes out (hot and cold... all faucets, shower, and toilet).
Here's a photo of our Keystone Springdale water pump before attaching the winterizing hose:
Here's the second hose with the fitting that attaches to the IN side of the pump. On this pump, the blue clip simply slides forward, and you pull the hose off. You then slip the second hose on and slide the clip back. I put a towel under the pump so the floor would no get drips on it.
Once you attach the 2nd hose, you simply turn on your water pump and let it start sucking from the gallon jug:
You turn on each faucet, one at a time and let it run till the clear water is completely replaced with "pink".
And remember outside showers and faucets too:
If your lines are clear, you can see where the clear water has been replaced with the pink stuff. This was after I reconnected the camper fresh water tank in- pipe:
You will want to remember to open your low-point drains under the camper. I usually open mine after pumping the pink and let it drain as much pink as it can. You can keep the pink in the lines, I just perfer to drain it while I'm right there.
Pink will freeze (actually turn into a jell) if it get's cold enough, but it does not expand. Water expansion is what makes pipes, valves, and faucets freeze and break. Pink doesn't expand and it pushes all the water out, thus protecting your pipes:
My current camper (Keystone Outback) did not come with the winterizing kit (hose) so I bought one and attached it permanently. I purchased it from the dealer the day I took delivery of the camper and it was the first modification I did (installing it). Here's a photo of our current water pump. The "thing" at the bottom of the picture is the valve I added. The clear hose is for the "pink" the white hose pulls water from the fresh water tank:
Here's a photo of the valve. Getting a photo was pretty hard as there is not much room around the pump like in my Springdale.
So it's just a matter of sticking the clear hose into the gallon jug of pink and flipping this valve. Turn on the water pump and let it go to all the faucets. When done, turn the pump off. Flip the valve, and all ready for next spring.
To de-winterize, you just fill your fresh water tank, and turn on the pump and let it run to each faucet until all the pink is removed and the water is clear and not foamy.
Good luck, hope this helps!