South Dakota possibly Texas domicile questions

You don't need real estate in Texas to establish domicile. The Escapees RV Club offers a mail service that provides you with a mailing address (and forwarding service) that's good for getting vehicles registered, a driver's license, the IRS, TSA, etc., etc. The Escapees web site offers a lot of good information on establishing domicile in Texas, Florida and South Dakota. There's also good information on the RV-Dreams web site.