I don't have a spectrum disorder of any type, but for whatever reason I absolutely cannot handle crowds. I melt down in a way that, despite my best efforts, I absolutely cannot diffuse. We say I have personal space issues, lol.
We've done the dessert party twice -- it has worked out VERY well for us. While it's certainly not worth the cost of desserts, it's well worth the cost to be able to see the show without risking ruining the evening. I would gladly pay for an uncrowded area with a seat, the food is a bonus, lol. I definitely agree with that recommendation.
But honestly, our favorite way to take in Wishes is in Fantasyland. We show up there a few minutes before the show -- ten, fifteen minutes tops, grab a spot wherever, and enjoy the 360* view. It's very uncrowded, even with more people stopping to watch as the show goes on, and although it's not being viewed "as intended," you're in the middle of the action and for us, it's no less magical. When the show is over, you are in the uncrowded back of the park and can easily hop on a ride with little to no wait. If there's nothing in Fantasyland that suits your fancy, it's easy to zip over to Tomorrowland or Liberty Square/Frontierland -- and then around to Adventureland. (Just beware the parade route!) We've done this on some of the very most crowded days (Christmas week, Presidents Day weekend,) and have had great success. Enjoyment of Wishes with no crowds, no party cost, and no meltdown.