You actually dont need to smuggle anything. Testosterone is 100% legal in mexico without any type of prescription or doctors note. In fact, you can download the delivery apps that they have there(similar to uber eats in the states) on your phone where the mexicans on a bike deliver stuff for you in under 30 minutes for $1-$2 per trip - they will go to the pharmacy and buy the bayer testosterone and deliver it to your hotel
If you want exotics like tren ace, superdrol etc then the mexican law states you need a doctor's note for these things.
But bayer and other pharma brand testosterone is available at pharmacies completely legal with no prescription. If you have trouble finding it just go to mexico city. They will for sure have it there in the capital. Again the easiest thing for you to do is download the app on your phone and search for it, and have a mexican deliver it to you rather then going pharmacy hopping yourself searching for testosterone.