We have traveled south after Christmas several times. I would recommend I-5 and watch the weather for a good time to cross the Siskiyous. We usually take US97 to I-84 and I-205 around Portland to get on I-5. That pass south of Ashland is the most likely place for snow. Rolling Hills Casino is a good stopping place. I would stay on I-5 until SR46 at Lost hills CA. Head east on SR46 to US99 then South to SR58. Check out the Orqnge Grove RV Park just east of Bakersfield. Head east on SR58 to Barstow where you can take I-40 east into AZ AZ95 (NOT US95 in CA) on the east side of the Colorado River is a good road through Lake Havasu and Quartsite south to Yuma.
