Since you are in the early days of construction, thought I would share this. I had a lean to shed, which I planned to store my tractor in, but in the end I put up doors to enclose it. I did this for several reasons, kept the squirrels out (they eat the wiring on my neighbors 60 dollar tractor), keep out some of the mice, we get heavy fogs and the tractor would be all wet in the morning and since me and about 50,000 other people have a key to my tractor at least now there is a lock on the door.
I used T1-11, because that was already on the other 3 sides. If I had no shed I would have used metal at least here there is a place that will cut the metal sheets to length. Hopefully, the place you are getting the sheeting from do as well.
Keep the pictures coming.