Cooper Mountain might be another typical urban activation as at first glance nearby Cooper Mountain Nature Park looks like the perfect place to activate --- but it's not actually in the activation zone. There is a great alternative spot across the street that makes this one-pointer worthwhile.
The summit itself is on private property for the area water provider and is posted "No Trespassing." Cooper Mountain Nature Park is on the other side of a saddle and so is not technically in the activation zone. But across SW Kemmer Road is a "greenway" a few yards east of the summit - there is a bark and grass pathway through this greenway connecting SW Jeremy Street and SW 176th Avenue. Go a few yards up from the path towards Kemmer and you'll have trees for antennas and not disturb the suburban dwellers or path walkers. The view below has the recommended activation site circled in red. Of course, you can also do a sidewalk activation near the water tower - but that's best for 2m FM with a HT.
You can access the greenway off of SW 176th Avenue (near the red arrow). There is a bit of QRN from home electronics at this location so you might not be able to hear all Chasers, especially on lower bands.