I would suggest a back up camera of some kind. I know you've budgeted your
trip, but my budgeting process differs from others. The trip is the most
expensive part, not the camera, not the film. If the photos are important,
saving money on an inexpensive camera that fails and leaves you cameraless
is what I'd call false economy. YMMV, of course.

Funny you should mention an inexpensive camera. For almost every trip
I've made into tropical rainforests I've carried an Olympus Stylus,
the cheap one without the zoom lens. I've taken about 30 rolls of film
on each trip. Never had to replace the battery. Camera worked all the
time. And I got adequate snapshots. Good enough to make into 4X6
prints that I gave to the others on the trip. Good enough to trigger
all the necessary memories. I once got within about 3 feet from a very
small flycatcher and took a couple shots of it. Photos showed
something but no one would know what bird it was. But that wasn't the
point. The point was that I carried the camera all the time. It fit in
my shirt pocket and was smaller than a cell phone. Don't think even
the P/S cameras that I'll be considering will be that small but they
might be small enough take. It's tricky carrying binoculars and a
camera because the binos have to be ready at a moment's notice. For
me, the camera will only be used after I've seen the critters with
binos. An interesting thing occurs with many people who take high-end
photo gear on wildlife expeditions, at least from my observations.
They often miss the bird entirely because they prioritize a photo
instead of an observation. But their photos are often wonderful. Can't
have everything, I guess. Thanks for your comments.