Do you have two drivers available?
It might be worthwhile to head back towards the AZ state line for your second rental ending at SFO. Change the dropoff location of rental #1 to Imperial County Airport CA; and make your second rental pickup at the Yuma AZ airport (about a hour drive between). Just make sure to pick up car #2 first, then convoy 1 and 2 from YUM to IPL for the #1 dropoff. Your second rental will be $90 all in for two more weeks.
If that's too expensive, you can stack CDP codes with the DRV5 rate code to get it even cheaper!
