I'll 2nd Goose Island State Park. Love it there and have stayed the past 2 years before moving in to Rockport for the winter.
You should be able to get your 40 foot rig in to Rockport HWY 35 RV park. They will park you in their overnight sites right out against the road. They have plenty of empty sites because most people can't get along with the lady that runs the place. Or perhaps I should have said she doesn't get along with her clients.
She has problems with everybody, but just pay your rent and don't inter act with her and you should be fine.