Way too much to carry on. There is very little overhead space. And not enough room by your feet for for a suitcase. Not even close. You can check with the bus companies about what they can put in the hold. I did see them load a few bags under there but did not do it myself so I don't have personal experience to relate.
Maybe someone else has done it and can comment. Or if your Spanish is good enough, you can check out the bus companies' websites. For that matter, I recall the folks at the Hyatt being very friendly and you might ask some of the staff there. IIRC, most of them spoke very good English.