Lake Skinner is the night. It is the county reservoir on the north edge of the vines, full hookups, and the sites go faster than the vans do, so reserve the site first and book the van around whatever dates you get. Then plan the evening around the gate, which runs 6 a.m. to sunset Sunday through Thursday and to 10 p.m. Friday and Saturday. That is the difference between a long Saturday dinner on the wine roads and a Tuesday one you have to cut short.
The tasting rooms run east off I-15 along Rancho California Road, with Calle Contento branching off it for vineyard-view blocks and De Portola's equestrian hills quieter to the south. From camp the wineries sit less than five minutes out. Nights stay warm this far inland, and the hookups are what keep the van livable after dark.
Book a dawn balloon and it lifts off over the vineyard rows at first light while the van stays back at the reservoir. The launch fields aren't for camping, so the flight is a morning out, not an overnight.
Lake Skinner Recreation Area
Lake Skinner sits in rolling chaparral and oak at 37701 Warren Road in Winchester, 199 full-hookup sites open year round. Reach it from Temecula on Rancho California Road east through the vineyards, then Warren Road north into the park. Each site holds up to six people and two vehicles, worth checking if the group is bigger than a van sleeps. Larger rigs for the same trip are on the RV rentals for Temecula page.
Palomar Mountain
When the valley heat gets old, Palomar Mountain climbs to around 5,000 feet of pine, fir, and cedar, cool in the evenings even in summer. Doane Valley is the state-park campground near the top, and Boucher Hill's fire lookout reaches out over ocean and desert. It's a slower, higher night than the reservoir, and getting a van up there takes some planning on which road to climb.
If you keep driving
East on Highway 79 the land opens into desert at Anza-Borrego, and that run is set up on the San Diego campervans page. Joshua Tree is a separate trip from the north, mapped out for Joshua Tree campervans. And to trade the desert for pines at Idyllwild, the Palm Springs campervans page runs the Palms to Pines byway.