Easiest snowbird route from Seattle to Phoenix in January

Stay at a hotel instead of in the RV when you get to Baker or La Grange so you can keep the rig winterized.

You can stay in the rv with it winterized. We just bring a pail of water in the shower to use the toilet. Keep the furnace on for heat. We only use the toilet, so we put a jug of rv antifreeze into the toilet to keep stuff from freezing. It would only be one night until you are out of potential freezing. No need for a motel when you are driving one.