What Heather's said:
Guest Relations - 407-824-4321
Please let us know how you make out! Good Luck...sending Pixie Dust your way!!!
Also do consider posting this question on the other board also, I do remember it being posted/asked before!! Wishes is a magical firework show, I would think you'd want to give her/pop the question before that, and just stand before the castle watch the fireworks and listen to "Wishes" Wishes...
Guest relations is sure to be helpful as this is a magical place!! I'm sure much of it depends on how much you want to spend (GIfts of a Lifetime can be expensive, but they can send you on a scavenger hunt, or help you with any other ideas you want to work with!) and how public you want it to be! Private - the Fort Wilderness has a carriage ride as does Port Orleans, around $30 as opposed to borrowing Cinderella's carriage,f or around $2400!!
Good Luck, but definately think about swinging around to the Grand Floridian and check out the Wedding Pavillion, and if you dont eat at the Grand Floridian you should at least make an order from their bakery to pick up to go (they mentioned the chocolate slippers, they're wonderful, if you do a search others have posted pictures of them, if you eat at the Grand FLoridian they will bring it to your table on a decorated plate! They also have wonderful chocolate dipped strawberries, decked in 'tuxedos' w/ a white Mickey Mouse... all at the Grand FLoridian...)
The possiblities are endless!!

The Lua at the Polynesian, the Contemporary Rest, overlooking the Fireworks/Wishes...