This is what I was planning to do with our new Ollie, same procedure I used with our Escape and Casita. Live in the South Texas, so we do get an occasional below freeze temp.
1. Drain all tanks (black, gray, fresh).
2. Turn the HW heater values to bypass,
3. Drain the HW heater.
4. Blow compressed air (40psi) through the lines to eliminate any water (taps, toilet, outside shower).
5. Run water pump for a few seconds to remove any water.
6. Pour small amount of anti-freeze in traps, including toilet (seal).
Our Ollie will have compost toilet and Truma HW, so the process will change a bit.
Still learning how to maintain lithium batt in cold temp.
thanks