I found a solid, skateable area outside of the THP8/THPS3 Downhill level in THUGPRO.
I used a "homemade" no-clip that I made with Cheat Engine to get there.
(I will NOT release it. Also, I DID restore the freecam as seen in the video, but I had to take the download down so don't bother asking for it, I just use it privately.)