You'd be surprised how many people "mind their own business" when it comes to other people's kids.
I do have one good story about boys peeking into stalls. This wasn't at
Disneyland but at a women's restroom in my local mall's food court. I was in one stall and a woman went into the next one, leaving her 7-9 year old son to stand and wait by her stall's door. The boy turned and started peeking into my stall and I gave him a nasty glare, but he didn't turn away! I told him to stop peeking and his mom heard and threatened him to keep his eyes to himself. He stopped for a few seconds but turned back again! So as discreetly as possible I continued my business, though I was fuming mad. And yes, other women were coming and going but no one said Boo to him.
I left before his mom finished her business. I wanted to wait around and give her a piece of my mind, but I was too angry to filter out what shouldn't be said.
Now, some would say that I should have left the stall and do my business elsewhere because a boy was watching, but I was there first, already a mess, and why should I leave? It's a women's restroom! At the time I was so furious, but later on I also felt a little smug that she had the clean-up duty of discussing women's reproductive organs and why they bleed.
He saw me remove and insert a tampon.
So my opinion is that if you don't want them to go into the men's room alone and you don't want them in your own stall where you can control them, then go to the unisex restrooms and wait outside the door.