I'd rather have something I can thrust with and have some power behind it, due to the space needed for a swing.A tonfa would be ok, but probably difficult in a place where you can't do firearms, and it lacks range. Swords and spears should not be overlooked, but but I'm not sure how the judge would react to it.

I'd probably take a short staff made of something like oak or one of the epoxy-impregnated wood products- balanced so I can use it like a sword, including thrusts, if I can't swing, but long enough that the staff techniques still work. Or the sword stand-in I use for building wrist strength- 1.5" dia solid steel rod, about three and a half feet long. Rattan is for when you are playing with friends, steel is for when it is just you and that shadow that keeps stalking you.

In any case, it isn't going to be something that isn't technique intensive.