Camping around Long Beach? Try Terminal Island. Kidding. The Federal Prison is there. the Long Beach coast, for the most part, is pretty industrial. Head down the coast just a little bit to either Bolsa Chica in Huntington or if I were you I'd head down a little further South to San Onofre.
San Onofre is a nice , more isolated beach with great surf.
Actually what just popped into my head was El Capitan State Beach or Carpenteria State Beach up in Ventura County near Santa Barbara. Camp there on the way down and then hit your cruise.
Dude. Seriously. You don't want to camp anywhere near Long Beach. Not unless you are homeless.