KLLR does not have on airport camping but there are several state campgrounds nearby, you WILL need a car or bike, see above messages on their car rental gig
Oceano 0Q5 has camp sites on the airfield, walk into town for food or walk to the beach. Beach is one of the few beaches you can drive on in CA so area has a bit of a redneck flavor but is still worthy
Shelter Cove has a Private campground right next to the airfield, also has some limited food options within walking distance
Half Moon Bay has an informal camping area at the south end of the field, has a firepit with wood, tables, and chemical toilet, water has to be fetched at the other end of the field or through the gate at one of the establishments in Princeton. Good restaurants in close walking distance, beach is also a close walk.
All four of these are subject to the summer marine stratus causing the field to go IFR, only KLLR and KHAF have instrument approaches. If uninitiated, the coast can warm and beautiful but also be grey and cold in the summer, -bring layers.
As a fogged-out alternative, I have also camped at Columbia (022) very nice campground and short walk into an old gold mining town, town is a bit touristy but has plenty of food options