There is a place down, north of Lockhart, TX that is about the most "rustic" RV park you can find. It is really just some old woman's property where she has added some facilities to allow people to have RV hookups. I stayed there for a while. She only charged $200 per month, with all the electricity I could use. I just looked, and can't find any of my contact info for her, other than this address: 270 Hidden Path, Lockhart, TX 78644
You can just drive down there one day and see if she is still alive. It won't be a wasted trip because Lockhart is where all the good BBQ is located.