One other item to note now that I'm listening to a working commercial structure fire in San Clemente is their talkgroups are on the Countywide Cell down there. While OC is a SmartZone system, they heavily restrict which talkgroups roam so leave the vast majority of your OCFA talkgroups on the Countywide Cell.
The exceptions are:
Laguna Fire 5G on the Laguna Cell, 5H is both the Laguna and South Cell
Santa Ana and Costa Mesa on the South Cell (3A-3E)
Metro Net North cities use 2N for structures which is on the North Cell
Hope this helps you with your monitoring.
-M142