That sounds like a cool idea, and it is possible though ARIS won't do a lot to make this idea super convincing necessarily.
One limitation is that the map players look at and play on is the map provided by Apple/Google. We do not have a way to look at a custom map (though if we can find a way to get about $5K together...).
That said, there are a couple options I can think of:
1) Find an existing high school and put all of your game triggers there. But in the story of your game, it is not really *that* high school.
2) Don't use the map. You could have a game that only uses objects in the game world and don't really connect to the real world at all. This may not draw on all of ARIS' strengths, but it might not be terrible. Conversations and the rest still work fine. It also might be an indication that another game engine might suit your purposes more directly.
Hope this helps and I'm excited to see what you come up with.