Rick
There is a KOA on US290 about five miles east of town near the community of Stonewall. Have not stayed there. This one is about three miles south of town on Tx16......Lady Bird Johnson Municipal Park. Stayed there several years back and it's OK.
http://www.fbgtx.org/other/rvpark.htm
There are more, I can't remember where all. You might do a search in Google to find others. Where ever you decide to stay I recommend reservations. Oktoberfest is a big party and lots of folks filter into Fredricksburg for the event.
Looking to get up with you one of these days as we're only 25 miles away. Things have settled down since the move up here so have most anytime free.