We stayed on the Bolivar Peninsula/Crystal Beach at Bolivar RV park. Decent place with good sized sites and FHU. It is wide open with lots of maneuvering room. The ferry will accommodate trailers and semi trucks so no issue with going across. Free too. We thought it was a whole lot quieter than staying right in Galveston. I will caution you to bring provisions for ant control around you rig. Its Texas, they have lots of bugs....and ants. I think I brought home a whole colony with me.
We traveled into Galveston when we wanted to quite easily and never had to wait all that long for the ferry. The best place we ate at  was Gaidos Seafood Restaurant. Fabulous. Have the bread pudding for desert. To die for.