I've just recently gotten into this process, and pouring, developing, sensitizing plates that big is an amazing feat. Getting an even collodion pour across a plate that big would be such a challenge. I'm doing 4x5" and 8x10" and its probably about as big as I'd want to go.
Gotta admire his method and dedication, and to be honest I really like his landscape work. He showed that portrait at the beginning, which is great, but to be honest, everyone in wet plate does kind of the standard up close and personal confrontational portrait (I'm guilty of this as well). It's nice to see some alternative uses for this amazing process.