Are there any touristy things you want to see in particular? After I get off my cruise at San Pedro, I plan to Uber it to Santa Monica Pier or Venice Beach to walk around and gawk at the weirdos before my late flight. Ha! You can store your bags at local merchants near the beach using an app like Bounce. I use it to store my bag at cafes, stores, etc. while hanging out in NYC. One time I used the app to store my bag at a photography studio in Manhattan. When I got there, there were tons of beautiful models coming in for an audition. It was worth it!
The app will charge you like $1-$2/hr to store your bag at the business, or a flat fee of $6 for the day. Something like that. The merchant will put a number tag on your bag. Take a picture of the tag & bag with your phone (good for proof for your travel insurance), or write it down. When you come back for your bags later, the merchant will ask you for your tag number and to finish the final check out on the app. The app will charge you the appropriate fee, and off you go! Take a final Uber or taxi to the airport. I've never had problems with it. That way you can enjoy your day and not have to deal with your bags!