The reason Olsen is off limits to stunts is that some silly XC jogger fellah got his size 13 stuck in one of the former features at Olsen. He sued, and everyone freaked out, therefore no stunts at Olsen.....
But, I did get a nice diving board ride there this saturday!
I really love the A2 local loop trails - you can easily dial in a 2 hour + ride or more if you wish, and the terrain is unlike anywhere in SE michigan. You sometimes think you're in another State entirely. I have a GPS map of this somewhere, but I really don't know where, but this map should show you what is in store for you if you tackle it. I didn't GPS track thru "the bluffs" trails however, but it's easy enough to find adjacent to the Main street/M14 area - trail access directly across the street from that Lotus company building/Lakeshore park rd. Caviat: the thing is, it's not really a marked trail, and unless someone shows you around, good luck finding all the little hidden trail entrances.
Which is why it's so unique - not too many trails around here provide the biker with a true adventure setting - you never know on what, or where you'll end up!
Here's a closeup of Olsen park: