For MNNSHP in 2012 my wings had a wire frame that extended from the middle of my back to about a foot over my head - 4ft of wire, and 6ft of shimmery cloth wing. I wore them into the park and from about 4pm to 7pm for photos. No one stopped me or questioned me. I was also wearing a full ball gown (I can post pictures tonight if you'd like), which is now against the rules. If it helps you can "wing check" at the shop to the right after the gates, where you rent strollers.
Before that, during an August visit I wore smaller wings made of wire hangers and cellophane wrap (stretch 4 hangers into 4 hoops, twist the hook part of hangers together in the center, with two on each side, cover the wire hoops with cellophane wrap, cover the center with medical tape). That was for an all day visit. I road BTMRR, SM, HM, and SM with those homemade wings and no one objected.