One problem: Yashica ceased to make this camera three or four years ago. But no worries! Due to the miracle of eBay, this camera remains a hot seller and a highly desired item (no doubt, helped by my steady one-man campaign). Originally it sold for around $160, but today a camera in fine condition sells for $200 or more. Even at that, it's worth it.
Now, you apparently have figured out that film is the way to go, even when you already own Nikon digital cameras. Why? One word: Batteries. All digicams of course need their juice, and they're power hogs to boot. While it may be possible to pack a solar charger, a camera such as the T4 has the advantage of, 1) not requiring a lot of power, so long as the flash isn't being used, and 2) using common 123A-size batteries that can be purchased in advance and stored for long periods of time. Chances are one battery will last for your trip. Two surely will.
So there you go. A good camera on your trip to do good.
For a phalanx of view-hungry gadgetry, check out Outside Online's all-new Cameras Buying Guide.