If you just want to try something different,
Coushatta Red Shoes RV Park is about $20 a night, located in DeRidder, LA area.
Highway 27 to Highway 12 in LA will get you into Vidor and pick up I-10.
Instead of going through Houston to get to Galveston, Take Hwy 146S in Baytown, TX. It will take you right to the Texas City Junction, pick up I-45 across the Causeway down to Galveston.
If you follow a mapping program it will want you to take I-10 to I-45 into Galveston. The Hwy 146S is a much less stressful route as far as I'm concerned, but living in the area I don't have a problem with the idiot Houston drivers. It's more scenic, a few more red lights on I-46, but you'll arrive less tired for sure.
From Galveston I'd head down the Blue Water Highway that runs parallel with the ocean into Freeport, TX, and then pick up Hwy 35S through Corpus Christie to Hwy 77S. But that's just me. There are more campgrounds in this area than you can shake a stick at. There is a new one just on Hwy 6 coming out of Galveston that is right on the Bayou. Either Palacios or Port Lavaca hs a new CG that other forums were raving about. There is probably a dozen CG's within 10-12 miles of Texas City.
We would enjoy sitting down to a good Mexican meal if you happen by the area. Even stop for a day or two.
Happy trails.
Edited: The Galveston State Park is open for business and has FHU. you can opt to stay on the ocean side, or go across the street to some nice bayou area. Galveston is a nice tourist trap. We enjoy going down there.
We just came through Sarnia about 6 weeks ago. Don't you just like those cement filled bolisters at the crossing? I had about 1 inch clearance with my mirrors on the passenger side, and I actually had to maneuver around one of the bolisters (is that the right word?) We also met some wonderful people from Chrisler, CA - both were RMCP.