you need to buy 3 HG to really slow the rush down.
The Lurker/HG player can also pivot to 3-pile on Estates/Lurker/HG instead of Duchy/Lurker/HG if they recognize they're going to run out of time, so it only slows down when the 3 pile happens. You still need to score enough in time as well.
There was a Lurker/Fortress/Advance/Hunting Grounds board I watched once, with engine vs pure Lurker/HG rush, and the Lurker/Fortress/HG engine got the win, but was only about 1 turn ahead. I am not optimistic about many combos outdoing what you could do there.