I think of a Field Camera as a lightweight wooded folding design such as a Gandolfi The Toyo and Wista models that you quote are (in my mind) Technical or Press cameras. Quite capable tools, but sturdy and robust. If you plan on hiking across the moors, weight will be an issue, and these two are heavy beasts.
I started out with an MPP MicroTechnical - It coped well for much of the subjects I shoot, but I found the range of movements to be limiting at times. In the end, it was me that couldn't cope with the weight so found a Wista wooden field at half the weight to be easier to lug around. Not quite as rigid at times, and a 300mm lens is right on the limit of usability, but so pretty.