I have stayed at the Paradise By The Sea park a couple of times. Basically a parking lot with marked spaces, and the train tracks are on the East side of the park. But, it's a close walk to the beach. Around these parts, any place near the ocean cost more and has small sites.
Like other said, the state parks at the beach are all booked by now. You can try and see if anyone has cancelled their reservations. Santee lakes is a great place to stay, I've done so many times.
There are a lot of places south of Lego Land. Do a google search and you will find quite a choice, but all are farther from Lego Land than the Oceanside parks.