To be a line-holding FO in LGB you will need about 2.5 years seniority.
The big problem is that the trips $uck and you'll be doing mostly red-eyes.
Another concern I have is that we will code share the crap out of CA with Alaska and possibly even close LGB if this TA passes.
So, if you want a SoCal base do what you can to get to the big 3.