I know at the NHRA Nationals drag races you can camp across the street from the racetrack. You will probably have to look on Sonoma Raceway website to find out the cost. Showers I don't know about. And I don't know if they allow camping at other events.
Yes showeres are at the race track at the towers. Theres camping inside upper level and at 50 acres. Prices vary
Yes dry camping, no showers or hook ups
On the information page for the track there is a way to ask a rep for the track. Maybe they could answer your question.
They have camping available which includes showers for the weekend package but you'd better get your tickets early cause they sell out fast. And that's for both NASCAR and NHRA.
Yes the showers as portable and to camp there you do have to have a ticket package of two or more days
Camping ya. Not sure about public showers
Thanks! Your answer is awaiting moderation.