Help establishing a route from PA to warm south west in Jan

We are also headed south in Jan with our camper. We are meeting up with friends from Home who have been snowbirding in the south west USA for 19 winters now. We are headed to the Yuma area, which they say is “usually” the warmest area in the winter. They camp on BLM land south of Yuma so that’s where we are heading
Going to be two long days of driving for us to get to the Lawn chair and short sleeved shirt area, and we can’t wait.
Soup.