Interestingly enough, the
Bloomington Parks map shows a tiny extension corridor of Tierney's Woods leading to the residential neighborhood on the south end. It looks like there might even be a vestigial parking lot. Or is it a drive way? Can't tell from the aerials. Will probably have to confirm on the ground. Perhaps one of the adventure runs could utilize this access point for variety.
...Actually the more I look at it, the more is looks like drive way. Anyways, you might want to check it out...The corridor may just be the pond....
View Tierneys Woods South Entrance? in a larger map
I also noticed a corridor of woods between Reynolds Park and Tierney running NW~SE could that be utilized? Perhaps a taped route through there? By taped route I mean you tape a course through the woods where the next tape is always easily visible from the last tape. (every 10 meters?) That way the runners find there way with no map, only by following a taped line. Real orienteering courses sometimes use this technique to guide runners on a precise line through dangerous terrain or private land. The taped route could be really fun! You could get creative and make it like obstacle course!
I can vet the 20th if you like, as I won't be in town for that one. Do you want me to do that?