As mentioned Texas beaches get better the farther south you go. Though if you are sticking with the Galveston area you might try on of the RV parks on the Bolivar Peninsula just north up the coast from Galveston. There is a free vehicle ferry that connects Galveston to the Peninsula (about a 10 minute ride), there is a lot of new construction on the Peninsula as nearly everything there was repeatedly flattened by hurricanes between 2005 - 2012 or so. Which has had the effect of turning it from lots of ran down beach shacks into a fairly nice place with actual stores, water parks, etc.