Original idea: Was to be walking by one of the random street shows they do and be pulled in and asked to stand there. Then have a Good character like Goofy or Mickey come in and hand her a balloon with a hidden ring tied to the string inside the balloon and a weight on the bottom so it wouldn't fly away. Then a villain character like Pete could come in and would pop the balloon. Goofy would then take the popped balloon place it in my hands and shrug his shoulders like "oh well" then I would open up the pieces of the popped balloon to revile the ring and drop down to my knee and ask her the question. Then Goofy could come back after I ask and hand her a new unpopped balloon. I also wanted to have maybe a friend or family member secretly there to photograph and maybe video tape the whole thing. I also had one last surprise to get us front row for the world of color show later on in the day. Anyways that was my idea but it doesn't seem possible now. I would be happy to do anything that would make her happy though. I want to involve the balloon some how because every time we go she always asks for one
My more realistic back up plan now is to do the thing with the photopass people and slip them a note that I will be proposing so we can get photos. I havent completly thought this through but I would go get the balloon and tie it to the end of the box or ring, and then have her wait for me somewhere while I got set it up and come back with the end of the balloon string inside my pocket like its caught on something, then hand the string to her surprize her when she tries to pull it out and get the string unstuck.
You should go buy a fairly heavy balloon, like a mylar, and the ribbon they use at DL and practice this at home. I think this is a better idea than popping a balloon because you don't know where the ring would land. You might try going to the photo shop to ask what time they will have the most PhotoPass people out at the castle, and tell them what you're planning. But I do have one question/suggestion. Will she be suspicious when you go off alone to buy a balloon? Stopping by the photo shop would also involve splitting up. Are you alone on this trip or can someone help you? Some couples spend every second together and for others, splitting up wouldn't trigger an suspicions.