I have stayed at THV. I would not stay there without a car. Like PP said, you take the internal shuttle to an SSR bus stop and then get off and wait for a park bus. Or you can walk from THV to the closest SSR bus stop in Grandstand but depending on where your treehouse is located, it could be quite a hike. For our location, it was quite a hike.
I have stayed at OKW. The bus transportation is very good there.