OP, your arrival and departure times are perfect. In my experience, late morning is when traffic is the lowest in the LA area during daytime hours. If there’s an accident, everything goes out the window. We always leave plenty of extra time specifically to allow for accidents. We also regularly check traffic reports on our phones. The benefit of so many freeways is that it’s possible to take other routes.
Thanks for the advice to book a rental away from the airport! I was able to snag a rental van for 10 days through Hertz for $44 per day. It was going to cost $49 per day but I signed up for the hertz member program and the price dropped. I also snagged a hotel room for the friday prior to our saturday departure home. Hotels.com had a 2 bd queen suite with a full refrigerator/microwave for $250 a night. A little pricey but I can cancel up to one day prior. The hotel offers free breakfast and shuttle to the airport about 1.5 miles away. So we can drop the van off Friday night and take the hotel shuttle the next day. No fuss no muss.
Now I just have to get the rest of our itinerary going. Excel spreadsheet here I come… 
Make sure the hotel van runs during the hours you need to use it. Some hotels may not start van shuttles until 7 am.
the TSA is security theater
and it will be a long summer for those flying in much of the country.
http://www.nytimes.com/2016/05/03/business/airport-security-lines.html
PreCheck is highly recommended even if you only travel once or twice per year.
Thanks! I double checked the van does run when we will need it. I have pre-check but the H and kids don’t. They can suffer together. 
We’ll get there early to get them through security.