I think you'll have problems flying a larger dog in cargo this time of year cuz of the weather, but each A/L makes its own rules.
I drove DFW - SMdA 22 - 25 April with a 40 lb dog. Stopped in Austin and Laredo which had animal friendly overnights.
Virtually all Mexican hotels exclude animals (most adamently), but the dog stayed in the car overnight in Matahuela (covered parking) without problems.
Your vet will provide the necessary international paperwork. No one ever checked as got "green lights" at each check point.
Like a car, a US trained dog can be a liability here, but you're probably used to the inconvenience of a dog in a city (a couple had their adopted greyhound flown from North Carolina via Leon/GTO earlier this year for a three month visit).
That's a LONG drive from Houston to SMA. It's a good 5 hrs, maybe a bit longer, from Houston to the border. I'm also not sure the requirements for brining an animal into the country or returning across the border from Mexico into the states. Be sure to bring all of your paperwork from vets about rabies vaccinations and all that.
The requirements for dogs and cats are simple and nearly all US vets have the forms.
I am traveling to SMA in August with a small dog. Has anyone here found a nice rental or hotel that accepts dogs? Many Thanks, Liz