The Ventura camping near the surf breaks serve RVs better than tents. Some of the RV locations require well kept campers and don't seem to allow sleeping in truck or SUV. But, here are several places where you can pitch a tent (list below). The first one is probably your best bet. It and the next four take reservations.
Private Tents & RV camp sites
Ventura Beach RV Resort – reservations possible; sometimes they have yurts set-up for rental
https://www.vbrvresort.com/tent-sitesLake Casitas Recreation Area – 15 miles north of Ventura
http://www.lakecasitas.info/You may actually have to call or email them to complete a reservation
This web page also tells you that local contractors will provide a camper trailer for you
KOA Campground – 30 miles north of Ventura
https://koa.com/campgrounds/ventura-ranch/Something different -- they provide the AirStream trailer within a small, privately-owned downtown Santa Barbara property; 30 mile northwest of Ventura
Autocamp
https://autocamp.com/guides/location/santa-barbara/Carpinteria State Beach – 16 miles northwest of Ventura; pretty busy & don’t think you’ll get a rental (but, you can try)
http://www.parks.ca.gov/?page_id=599The web page also tells you that a local contractor will provide a camper trailer for you
County Tents & RV camp sites - 1st come, 1st serve during May to Memorial day. Show up on week day at just the right time. Call the parks to inquire when the right time is
Faria Beach
https://www.ventura.org/parks-departmen ... each-park/Hobson Beach
https://www.ventura.org/parks-departmen ... each-park/