Just take it, stick it in your backpack, and let it stick out. Worst case, if security stops you, rent a locker and stick it in there. That’s actually what I’ve done with mine anyway until I was ready to use it. Don’t fret about taking up the footprint of a tripod. People will have giant strollers everywhere and take the kids out of them to hold or put on their $&&@“$#% shoulders right before it starts. You’ll be fine!!
ETA: And I’d be more than happy to just purchase a DVD of the fireworks instead if Disney would just take my money!! No clue why they don’t capitalize on that.