Help decipher camera from picture.

Guys, it's definitely an Exakta. It doesn't have a conventional top plate, the body is full width with the mirror box, and there is a rewind knob on the bottom of the camera. It won't be anything else. Besides the book "One Man's Wilderness" makes several references to him using an Exakta. It's an Exakta.

Take a look at this sideview of a slightly older Exakta: http://www.flickr.com/photos/urmelchen/4236011947/
Even though it has a WLF instead of a prism, you can see the slow speed knob on top, the rewind knob on the bottom, the chrome hinge, and probably most tellingly the chrome strap lug standing out against the black paint around the top of the camera (no chrome top plate as on most cameras).

The lens is also almost certainly the 300mm Meyer Orestegor: http://m42.org.ua/407 the silhouette is pretty distinctive, and note the location of the rings.

All types of Exacta cameras that might fit have a straight hinge, the one in the photo has an irregular outline. As long as this can't be explained otherwise it won't fit to my understanding.

The Exakta film door is chromed, it may just be a bit of torn leatherette revealing the chrome beneath. Given he was hiking around mountains and the camera was already over a decade old by the time that image was made, it seems perfectly reasonable.