From what I've read, and from my experiences, Disney can & will do anything as long as you let them know what you need. You can have many things delivered to the room, you can have CM's available to take pictures of proposals (my friend has this done) - just let them know. Call the Poly in advance & let them know your plan, or if you do the Illuminations cruise, tell them about it when you make reservations.
Also you might want to check out disneyflorist.com - as you can have all kinds of baskets & flowers delivered to your room. Some are very unique & romantic! I have a wish list there myself! =)
Congrats!! :sohappy: