I would guess, assuming that you would be heading out with a guide in Mexico, they'd be able to take both fly rods and spinning gear, if your flycasting was not working.
I love to flyfish. Few things I enjoy more than walking a river, trying to outsmart trout.
Fishing the flats of Isla Blanca a few years ago.
As far as a beginner set up, I'd hit some shops & talk with the locals of where you plan on using it and what you plan on going after. Then you can start casting them, see what feels good, get some free casting pointers and get what feels right.