I ran my stock '04 at this event a couple years ago. Factory roll hoops were acceptable on a vert then. I hope they are not changing that ruling as it will eliminate a lot of cars.
Are you very, very, very height challenged??
Independent of what the track rules are, you should be concerned about your safety. Specifically, whether or not your head will be snapped off from your neck in a rollover!
For this, go with the "broomstick rule." While you are seated in your car WITH your helmet on and the top down, have someone place a broomstick on the top of the windshield and then place the other end of the broomstick toward the factory roll hoop. If the broomstick first hits the top of the factory roll hoop and leaves a couple inches of clearance between the bottom of the broomstick and the top of your helmet, then you are probably OK. Otherwise, your HEAD may be the first thing to hit the ground in a rollover.
Not telling you what to do, just trying to suggest some things for you to consider.
Also, on fluids and brake pads, these things should have been changed long before 15k mi. If you go through pads at the track, in addition to the grave safety concerns, you will also go into your rotors. When you go into your rotors, you will most likely need to change your rotors.
I would only go to the track with fresh fluids, new pads and new or almost new tires. My goal is always safe fun!
Good luck on your track day!