Thunder Mountain is a fun ride actually. It wouldn't work as a payload map without being heavily rethought though.
Can confirm.
Funny story, one time, I was on Big Thunder Mountain Railroad, and the ride broke down right around the final turn. As compensation, I was given a Golden Fastpass, which is a ticket that you can use for any ride queue to enter a shorter queue for the ride.
This all happened immediately after having to walk off Splash Mountain and through its behin-the-scenes sections, and getting a Golden Fastpass from that. Fun fact- most of the Splash Mountain ride doesn't take place inside of the mountain itself, but inside a different building to the side.
Honestly, there's a lot to be learned from the theming of rides like Big Thunder Mountain Railroad. All of the detail at Walt Disney World acted as inspiration for me to begin mapping- I wanted to create worlds that told stories.