does anyone know how to do this properly?

Not possible because the galleries must be built along the fence. Even if possible you would face AI issues with guests and staff; I thought it would be nice to have a large figure eight path in a park, with the center paths being one above the other, but the game recognizes that as just one AI path on the ground so did not differentiate between the upper and lower paths. (A path can cross over another path with no problem, but not run along above it.)