Further the chickens. Retire the sad lame jokes about Mexican bus lines. They are modern, luxurious compared to sketchy Greyhound buses north of the border and are am excellent way to get around Mexico. I personally have taken them from Can Cun down to Belize and from Ajijic to Mexico Court and Mexico City to San Miquel de Allende. Clean, comfortable and fast.
Just keep to the one suitcase limit and you are totally fine. One carry on and one checked suitcase. Keep it simple.