If you go to
https://www.mygmrs.com/repeaters you can search at the top. I put in Elsinore and got a hit, last updated a year ago. That entry says it requires permission to use it but, as I said, that was a year ago so things could have changed. Reach out to the owner to inquire before attempting to use, though, just in case.
There is also a GMRS section on RepeaterBook.com now.
The most accurate list of GMRS repeaters is the one you make yourself.
MyGMRS is woefully outdated.
Same for all these other "list".
The easiest way to find repeaters in Ca. is to listen and scan the repeater channels on Saturday and Sundays. You will hear all those noobies asking for radio checks, and announcing they "are monitoring".
Next...
You scan for the PL's. Most the "open (a farce) repeaters" will have the same input and output pl's.
Once you find a pair...then just key-up and ask for a radio check.
OR...
You could key-up and actually start a convo about politics or some thing fun. That should get the channel hopping real quick.
Don't forget to snag the PL's of the spanish repeaters too.
Any port in a storm.....right?
One thing though...
Lake Elsinore is in a bit of a radio hole, unless you are up in the hills.
Try the "Crest" Repeater on Mt Santiago 462.675 141.3pl you may be able to hit that one.
Crest is pretty much open now since all the paid members bailed when the owner booted many for missing mandatory "Band Practice".
The point is...
Socal GMRS changes on a DAILY basis. Machines go up...and boxes go down.
The "list" are useless.