As pointed out, read some crazy guy journals for some background. I have RV'd that part and a lot of the TX farm to market roads on that route are good. I don't know how you are going to get out of Houston. I know there is Brazos Bend SP where I would stop the first night leaving out of South Houston (or League City where I am for the next month or so) if not going to Galveston first. There are also some Lower Colorado River Authority parks and Brazoria County parks that have free camping or if you are going to motel it, there are places all along there. I am not too sure you get all that close to the gulf though as the roads seem to run a bit inland. Tons of RV parks if you want to take that approach and try and get a tent site at one. Sounds like a nice easy starter tour.