It's about 30 miles longer, but you can bypass most of Los Angeles by taking CA 126 north (east?) at Ventura towards Santa Clarita, I-5 south to CA 14, then CA 138 to Cajon Pass and I-15 / I-215 back to I-10.
I used this bypass when I was working in L.A. and had to drive from the San Fernando Valley to Indio instead of taking I-10 or I-210 through Los Angeles. Mostly light to moderate traffic and no mountains except for a short climb towards I-15 on 138, and it's 4 lanes now.
Use the Truck Lanes to get from I-5 to CA 14. The turnoff from CA 14 to CA 138 is called Angeles Forest Highway / Pearblossom Highway. Follow Pearblossom Highway north until you reach 138. The split from I-15 to I-215 south of Cajon Pass is opposite of what you'd expect from looking at a map, Caltrans re-did it a couple of years ago so I-215 splits off from the RIGHT.
These are mostly 4 lane highways and you'll miss the central L.A. hassles. Leave Lompoc around 9:00 - 9:30 AM and you'll miss the morning commute traffic through Santa Barbara and crest Cajon Pass early enough to miss the afternoon commute through San Bernardino.
Put in the waypoints shown in this map to get Google to map it for you.
