Deerview windows work very well and their door kit is nice. Old rv doors work as well. I built one 5.5x7.5 and another 6.5x6.5 and will build a 6x6 next time (cut 12’ lumber in half). 4x8 is Very tight and the longer blinds are difficult to see everything with one person. I can take two kids with me or two adults fit easily in my 6.5x6.5. Agree with using metal roofing and t111. Make sure you put the door and stairs so the water from the roof drains somewhere else. If insulting, space your studs accordingly.
Good luck.
