Any trip with a guide includes solid cloth hammocks, mosquito netting and a blanket. If it is winter in the Northern Hemisphere, you might want a light sweater to sleep in.
Any time of year you are likely to enjoy a hot drink in the morning. Hint - a chai latte from a powder mix tastes wonderful there, but you need to bring it.
It is now possible to have a quick cold shower, but you may need to pay the guards 10 Quetzals.
Hammocks, mosquito nets and blanket provided. If rain is possible, your guide should put a tarp overhead.