The simple answer is yes, it needs to be winterized. Any place where the temps get below freezing can cause a myriad of problems.....split water pipes, ruptured storage tanks, etc. Everything should ideally be drained just in case you get a cold snap, or have potable antifreeze pumped through. Texas does get freezes....even Dallas and out here in the West Texas desert.
Now....if you still want to use it during the winter (like most of us Texans do), here's an easy solution. Assuming you store the rig at home, you can leave it plugged in to AC power and put a small electric heater inside. Set the thermostat to where it keeps it up to 40 degrees or so, and you'll have no problems with the inside pipes. Make sure it's far away from anything combustible though. And it's still a good idea to drain the holding tanks after each use.
We love to go boondocking in the winter. There are several campgrounds open year round in Southern New Mexico, and most are virtually deserted in the winter. Fill the propane bottles, bring extra fuel for the generator, and crank up the furnace at night. Winter camping is the best. ;D