In England they're planted either in 8' wide corridors with 4' between plants (Kent), or 6'6" corridors and 6'6" between plants (West Midlands). (There are names on these traditional layouts but they escape me)
It's better if your poles have a T shape and you can run two horizontal lines between them, and then you run two vertical lines up to each horizontal, giving 4 lines per plant. On each line you'd have 3 to 4 climbers.
Sunlight all day long and orientation doesn't really matter that much.