You could try this FB page: https://www.facebook.com/groups/SAGeo/ It's the San Antonio Geocachers.There is also a CENTEX cachers Yahoo group that I've followed long before moving to the Hill Country, but it doesn't have much activity these days.
The old puzzle cache is a pretty long hike. I did it last year with RRM10 and another Kerrville cacher. We ended up with about 8.5 miles according to my GPS log but you could do it with a little less distance depending on the route you pick. Larry's earthcache, and the nearby official park cache are just a short distance from parking and the monkey rock cache mentioned earlier by TFP is a relatively short hike. If you go to the park website there's a .kml file of the park trails that you can look at in Google Earth and get a better idea of how the trails relate to the terrain and caches if you load them into GE as well.
We won't be able to take long hikes because our Brach dog will have to stay in the rv and I worry about electric getting cut and/or the a/c going out with him in it. I do have the puzzle, Earth, SP caches and Monkey Rock on my wishlist. We're just going to have to get to them on seperate hikes. Also, Garner- been there several times before we started Geocaching and would like to get a couple target caches there as well if my prayers are answered and a cool front unexpectedly blows through!
Do yall have an association/forums for that side of the hill country? I found only one geared more for the Austin area.
The last several times I've been out, I've sprayed by feet and legs with Deep Woods OFF, then put on my socks, sprayed again, then put on my boots and sprayed my pants legs and boot tops. Seems like overkill, but I got ZERO chigger bites -- and we were in some very chiggery places!