Do NOT "stealth camp" in a parking lot in LA. Very dangerous. RV parks are safe. The vast majority of people in LA are very nice. A few are not. This is a quote from the LAPD site:
"The County and City of Los Angeles are the “gang capital” of the nation. There are more than 450 active gangs in the City of Los Angeles. Many of these gangs have been in existence for over 50 years. These gangs have a combined membership of over 45,000 individuals."
That figure is far less than one percent of the population of LA County, which is roughly 12.8 million. But 45,000 criminals is not trivial.