Those dates are about firm as jello for me. Hidden pond was a very nice place. We had a little weekend trip there with FLrider, Lilricky, Black Wolf, and myself. The pond is really nice and cool if you're willing to head for the far end. The bottom is "muck" so having some kind of little float would be nice.
The Pat's Island trailhead was pretty far off the beaten path. I don't believe anyone had any issues leaving their vehicles unattended. The trail doesn't have a lot of shade so you'll want to avoid the heat of mid-day.