We went to South Dakota for our summer vacation and found a skate park in Custer South Dakota. The park is free and is part of the Custer City Park. Very easy to find 1 block off the main drag of the town.
I am attaching some photos of Steven Gough (Green shirt) and Nick Antonnucci (white shirt) while we were at the park. Thought you might want to add this to your website of skate parks in South Dakota. - Annette G.