Depending on how many people are hunting on the property, I would make it big enough to clean at least 2 deer. Also, if you have any manufacturers of pole barn trusses see if they can just build you a 10’ set of trusses or buy a 12’ set of lean to trusses. If you don’t have water I would consider a gutter system run to an elevated 55 gallon drum with gravity feed.

I would close in 3 sides and leave the south side open. Help keep the north wind off