Haven't been to Guatemala in years, but have spent a fair amount of time in the jungles of central and south america.
The "barba amarilla" (Fer de lance) is poisonous, but not really that aggressive. The locals will tell you the kinds of places to avoid.
Take the latest malaria drug, and don't listen to anyone who says they aren't good for you. Malaria is much worse.
I'm sure the team you are with have the kidnappers and drug runners figured out, and how to avoid them. They won't be that noticeable.
I don't think a large format would be much fun though. Imagine being under that dark cloth and trying to make camera adjustments with hot, sweaty and salty hands.
Don't drink the water and don't go barefoot.
Try and learn some basic Spanish. At least the pronunciation. It's a very phonetic language, and they don't speak too fast in the countryside. Cerveza and "Banyo" (phonetic spelling, haven't got the little thingy on top of the n) are the two most important words.
Fill any empty parts of your suitcase with toilet paper. The stuff they sell there is marketed here as sandpaper.
You will find the local people very nice. They have lots of religious holidays there, and some nice costumes they wear at every opportunity.
I would go in the blink of an eye. Have fun.