From what I've heard, Horseman field cameras are pretty well thought off. They made both 4x5 (in inches) and 6x9 (in cm) cameras. I'm guessing that the lens is marked 105mm or 10.5cm and therefore this is a 6x9 camera. I think a 6x9 camera is ideal if you hike in but film choice is a bit more restrictive.
The Seikosha shutter suggests an older lens. Expect that the shutter may need service. Also, parts for Seikosha shutters are, as I understand, no longer available except as harvested from one of the millions of other Seikosha shutters out there.
I do remember reading that there was some issue about film back compatibility with Horsemans and even different models of Horseman. I may be mistaken.
If the lens is 105mm (or 10.5cm) and the camera is a 6x9, you might find it a bit long for landscapes (it's roughly a "normal" lens). In my opinion, you need to get down to about 75mm to be useful. But much depends on the location and your personal style.
If you don't get the Horseman, you may want to consider a Century Graphic, another 6x9 press camera.