Is it normal to want to have sex in a bathroom stall?

That's a wonderful way to get arrested, OP.

Shes underage. Leave it alone.

Wow, a world class thinker is what we have here, folks. He'll get his rocks off with an underage chippie, in a bathroom stall, where they'll surely be caught. Then he gets to be the "young thing" for a half dozen prison "buddies" and when he gets out he can be on the sex offender's list for the rest of his life.
Go for it pal, with your intelligence, I can't see you contributing to society all that much, anyway.

If you have to use the words "making her agree", you need to not do the thing.

...
I am so glad my parents never sent me to summer camp.

You can't make her do anything she doesn't want to, and she's too young for you, creep!
>:-(

Do it and then inform her dad afterwards.

fear not, I have advice. What you need to do, in order to solve your problem, is purchase a rubber band, not one of those pussy ass, useless, skinny ones that they use to wrap a newspaper...but one of the industrial sized thick ones. Proceed to wrap it around your scrotum until it's nice and snug...this is important, as a tight fit is necessary. You may feel some tingling and numbness at first, notice a possible color change, but fear not; this is perfectly normal...you'll want to leave it on for 5-7 days, until things turn black, crisp up, and eventually fall off. This should quell your urge to rape minors in bathroom stalls and enrich your life for years to come.

No need to thank me.

The OP never said what state he is in.

The majority of states have the age of consent at 16-17.
Assuming that she is a minor without knowing the details is just idiotic.

And please don't call it rape. Two people who consent to sex can't be raped.

That's called rape.

Perhaps you should wait until you're 23.