I like the 8 feet tall that way the wind is broken aways away from it to short and it won't do much.I don't know the exact reason for the gaps inbetween but ours are all 1" apart.We have a neighbor who uses semi tires weld a 4" tube to the rim and fill with cement then he bolts a few boards horizontal then attach's the wind break boards vertical.He has quite a few of these and can set them up any where needed as they are portable.