Hi all,
I have been to Buttercup Valley in recent years (thanks to Mike and other for the help in locating the site), and you can in fact locate the exact spot where the set was constructed today. The chain-linked fence that once surrounded the set for security can still be located with a metal detector, as the fence posts were cut off at ground level during the set strike, rather than being completely removed. Those posts will probably forever mark the location.
Once you realize you're in the right spot, there is foam, wood and debris on the ground, I'm sure even now. Evidence of what once was....
Best,
Brandon