Everything is possible, but unless you’re in for some major winter mountain experiences, it won’t work. San Jacinto through the San Gabriels will likely be under a lot of snow and be freezing cold. The lower desert stuff in the first 150 miles is more reasonable. I did Campo to Warner Springs in winter last year, and i had days in the 60s and nights in the 20s and 30s. If a storm hits, and they do sometimes, add snow and drop those temperatures 20 degrees lower. But MOST of the time in winter, those first 150 miles should be very nice. The same would hold true for Section E Agua Dulce to Mojave.
markv