A couple I haven't seen listed by others.

La Rejouissance (I haven't done this one before, but know others who have sworn by it being one of the easier ones)

The Piper and the Captain - I've just about pulled this one off with our NV HS Band years ago. Hard to find recordings, email me if you can't find one stevenrash AT gmail.com

Egyptique - It's not overly difficult, but if your kids can't find the key and the chromatic notes don't play it. It's the same line over and over again, and if you miss it once we know you're toast by the first fifteen measures.

Another option depending on your past ratings at your school might be to enter a classification lower? Instead of as a Varsity, enter as a non-varsity? If you can play a Grade 1 instead there are a few more pieces that might fit you. I honestly would be considering not going to UIL otherwise.