I am making a park entirely from scratch in Sketchup, with the intent of putting it into THUG PRO once those kinds of tools are available, and I thought I'd record progress of the level's creation here!
So I thought I'd first start with an Imgur gallery to detail the process and how far I've got, and you can find that here
http://imgur.com/a/D8hYESo that's how it is so far, and I'll update this thread with more pictures as I make progress. Feedback would also be greatly appreciated!