What's the advantage to the OP for telling the "full truth" here? As far as I can tell from the thread, it looks like she would get more scrutiny and possibly wind up with a result that she doesn't desire - all at the whim of an overly zealous CBP thug who has an inflated sense of self worth.

If I were in her shoes, I'd be tempted to answer with something like "visiting friends in Ohio, Tennessee, and Las Vegas this summer before starting college at xxx university in the fall". Nothing said there is untrue.

If pressed for further details, I'd suggest that the OP have researched the names of some forests and places in Ohio and Tennessee where camping would be good - if taking a camera, she might also want to mention that she's a nature enthusiast hoping to get some great pictures to share with friends back home. That would further demonstrate ties to home, and an intent to head back there.

I'm still surprised that CBP would even care about any of this. It's ridiculous for them to get involved and prevent someone from entering the states simply because they think that a person might be coming here to marry and get a green card... So what if that's their intention? What's the big deal there? Thousands of people enter this country illegally every year; at least someone coming to marry and apply for a green card is doing so within the boundaries of the law. I'd suggest they stop wasting their time looking for idiotic things like this and instead spend more effort toward preventing people from illegally entering our country. The benefits to those actions are much greater.