Welcome to iRV2 .
Weather , any of your routes , could have bad storms in January.
I've driven through Nevada , from Jackpot to Vegas in Dec and seen just a dusting of snow on the side of the road .
Same route in Nov. and been plowing through 8" on the road.
I-5 in OR in Dec . 6" of ice in Grants Pass ( luckily in my van ) three weeks later bare highway in the coach .
97 to the I-5 in Weed could be the most predictable . But there could be issues going from Bakersfield to LA, or even Bakersfield towards Nevada on # 58.
But checking for a four day good weather window , and being ready to hunker down in place for several days is very important. No matter which route you choose .