I've never been in that boat but if you don't want an exorbitant Uber, it's probably cheapest to either get a hotel and take Amtrak in the morning or just rent

I've never been in that boat but if you don't want an exorbitant Uber, it's probably cheapest to either get a hotel and take Amtrak in the morning or just rent a car. LA and SD are close enough that it often won't accrue any "one-way" fees