A big thank you to everyone who responded to my request for information in the previous blog post. I intended to send everyone a mail back, but the response was larger than I expected, and it seems like I would mostly be writing everyone the same answer.
There were some discrepancies between all the reactions I got, probably because I forgot something important when talking about habits in the US: it's a big country. Some of you did specify the region you're talking about. Thanks, as that was helpful.
I think I can summarize the answers as follows. Carwashes to sponsor a school activity do exist, but bikini carwashes are more likely for stripclubs or college students (in that order) than for high school girls. They're a lot tamer than what you see on TV. Most people seemed to agree that it's more a thing of the past than the present (whatever the reason).
What I think literally everyone thought important to mention: just write your own fantasy, as it will be better than the reality. I appreciate the encouragement, but there was no need to worry about that. I already know (and knew) what is going to happen in that chapter. The reality - whether bikini carwashes never really existed, they are all out fuckfests or anything in between - would only change how I'd get to the fantasy that's ready in my head.
I think I said something earlier about the timing for posting that chapter. It's definitely going to take some time, as I'm currently working on three different chapters for three different stories. And for some reason, I was more productive before I went on a short vacation than now that I've returned.
Again, thanks for your help, to everyone. I'm pretty new to this site, but it showed people aren't just here to get their rocks off, but also to help each other out. Would it be a stretch to speak of a community? I'll leave that open for now.