Burbank Airport is another choice but the price is usually more than flying out of LAX though not like Ontario in my experience. You can get to the Burbank Airport quicker though from Lone Pine but it's still going to be about a 3pm arrival time. LAX would be a 5pm arrival time. This is using the Crest bus to Lancaster, Metrolink from Lancaster to Burbank or Union Station, Airport Flyaway bus from Union Station to LAX arriving at 5pm.
Frankly, with traffic issues it might be the quickest way. I think the nearest one-way car rental is in Inyokern/Ridgecrest where the Crest bus stops.
There are daily flights out of the Mammoth Airport also. Going to LAX and other airports. Few people seem to consider this as an option. I know when I checked into awhile back it seemed like a great option for getting to LAX.