One near me is having an issue with rats. I think really they just need better trash pickup mainly, and better shelters in general, but they've specifically asked for help getting rat poison. Would bait boxes with poison even make a dent in an outdoor environment like that? I can't singlehandedly improve the cleanliness of the camp or get everyone rat-proof shelter obviously, but I feel like just going straight for the poison could have adverse consequences and not be effective, potentially.
Getting plastic bins for folks tents is probably the way to go like others here have posted. 5 gallon buckets with lids can probably be had pretty cheap or even donated. Then bait boxes for the rest.
Gotta eliminate the food sources.
Rats will gnaw through plastic like nothing. Sometimes they eat plastic just for fun. If there is already an infestation some buckets aren't going to do a thing other than turn into trash.