I have a P/T in MI I notice that there is a red and white hose with a screw on cap from the bottom on each hose of the trailer, this is not nowhere the hot water tank. Is this is another way to winter...
When you open those low point drains, also open the faucet, farthest from the drains, to allow air to get in the lines. You still need to use RV antifreeze to protect drain traps and pump some into the plumbing lines to protect toilet valves and water pump. Don't forget the outside shower !!!
Draining lines, prior to pumping in antifreeze, prevents that water from diluting the antifreeze.