Many of our CA state parks offer a dump station and potable water. Get your self a "very quiet" generator or invest in a solar system and a Barker Tote-along and you can manage in those parks quite well with essentially full use of your trailer.
The only place I know that is full hookup, but offer a bit of elbow room is Camp Edison at Shaver Lake. You may want to look into it, reservations are bit antiquated but it's a great spot.
Other wise look at the Army Corp of Engineers (COE) parks. They often have sites with various levels of hookups and a bit more space. In CA these are often at Sierra Foot Hill reservoirs. A little to hot for our taste in the summer so we don't use them often.