pater47: Well, after roughly 600 calls, the official answer is - yes - you can still go back to the cave mounds.....but you have to have a tribal or game Warden escort. Since this isn't very practical, I've decided to archive what has to be my favorite hide.
In other news, I also found that they've completely re-done the gazebo - which means there's a 99.99% certainty the cache is gone anyway.
In other other news, I also found out they're going to re-do the old bridge trail through the swamp from the little mound (the one everyone knows about) to the cave mound. When this is done and opened back up to the public, I'll likely resurrect this as an earthcache.