I’m only going to scroll so far through your post history and I didn’t see your explanation, so sorry for making you repeat yourself. That said, I think solo is the wrong word for it if they’re explicitly there so you aren’t alone. Just say you’re on a trip, there’s no shame in that.

You can emphasize that you’re on your first trip without your parents, that’s still a pretty big step towards independence, but I’m going to fixate a little too hard on it being a solo trip you’re taking with friends.