Tri-Circle-D: My DD's are 10 & 7, will they be ok for this, or will they freak out? Thanks for any info you can send , without giving it away I understand!
Your daughters are the perfect age!
My youngest DD's were 9 when they did this. It is good Disney fun! A little spooky, but no real frights.
They still talk about it.
I am going to give you a spoiler here, so you can make an informed decision as a parent.
If you want to be surprised, don't read any more.
OK, here goes:
The hayride begins as an ordinary hay ride. There is a castmember in a cowboy hat who begins the drive. You head back toward the Wilderness Swamp Trail (behind the Settlement Trading Post).
As you enter the trail, there are props such as signs directing you to Sleepy Hollow. A gentleman dressed as an old time undertaker is standing next to the path with a lantern. He asks to board the wagon. The castmember accommodates and lets him on.
The gentleman then begins to tell the tale of the legend of Sleepy Hollow. You know, Ichabod Crane, the headless horseman. The gentlemen who do this are obviously professional actors, and they are great. So, the wagon goes along. And the story develops.
As you come to the bridge behind the 300 loop, the story reaches the point about telling about the headless horseman, and how he is searching for a head. We learn that he hangs out around here, but lucky for us, for some reason, he cannot cross the bridge. Then, we see him. On his horse! He is just over the bridge! Dressed in black, holding a glowing pumpkin in his hand! He rides toward the bridge, but he cannot cross it we are safe.
So we turn to head back. We are out of danger! Wait, what is that? Do you hear horse hooves? OMG.

he crossed the bridge, and he is chasing us!
This is the best part! The headless horseman comes right up to the back of the wagon. We were sitting in the back of the wagon. My kids screamed their heads off!
Then, the headless horseman goes away, we let our passenger off, and all is safe.
Of course, when we are done, the DD's say they really weren't scared. Right, whatever you say.
Do it.
TCD