I can find nothing else at this time. Not even a 'lake' on a map. I have seen posted by others looking for some old pictures that none have been found YET.
After the park closed, it was used solely for the purpose of the movie. The park was demolished sometime after the movie was completed. The site is now called Emerald Lake RV Park. I asked the Owner Betty Nastasi how it feels to be the owner of a place once used in the movie. She says It's very nice here; people come out here all the time and ask about the movie.
If coming from Austin, you would exit Yankee Rd. The entrance where Stretch comes into the park with her Jeep is the first entrance off the service road. However that entrance is now closed off. The RV Park uses the next entrance. Near the entrance Stretch used, is a concrete slab with eight wooden poles where you see her in the movie, briefly stop and watch the killers enter the Matahorn. Although those poles are now cut, this is definitely the spot where she stood in the film. The beams Stretch is running under while being chased by Lefty is no longer on site. From looking at the movie I would suggest somewhere beside the caverns in where the beams used to be, but you know how movies can be edited, so who knows.
The only other thing I saw on site was the railroad tracks that were used for the train in the amusement park. The amusement park also had a restaurant and a fishing lake in the back along with paddle boats, and go-carts. This would have been a cool place to hangout.