Dave and Linda, We spent last winter in TX. I have to say, the people there are the friendliest you will meet anywhere. They really appreciate the Winter Texans (That's what they call Snowbirds). Most of the COE parks will accomodate your size rig. Most even have concrete pads. If you like natural surroundings, you can't beat them.
Also, many of the state parks in TX are nice as well. Make sure if you are planning on staying in TX State Parks, that you purchase the yearly pass or you will pay an additional fee for both you and the wife every day on top of your camping fee. It might be about $60 but well worth it. We stayed on Goose Island State Park near Rockport and also close to Corpus Christi. We had a site right on the water and loved it there!
To find out about the COE Parks check out
www.recreation.gov. You will be able to find out if they have sites that will accomodate your size rig.