I've spent an hour easily at MEC inflating and laying on various mats before I got the neoair. There are numerous neoair models, but no matter the model of brand, actually blowing up and trying diff positions on a pad is the best way to go, plus you can see the rolled size.
Obviously a less busy time is better.
Going down the coast then into the various central American countries you'll encounter a big range of temps.
Quite the trip idea, have fun planning it.