That is a lot of specifications for any plant to fill. The most difficult is the narrow width. There are some really narrow evergreen junipers but you'd have to plant a lot really close together to get a hedge. There is also a yaupon that is very narrow but it tends to get more open in time and also would have to be planted en masse to get a solid hedge. If you can take a little more width you might like the effect of a clumping bamboo or perhaps a 'Bright N Tight' Cherry Laurel but it will take pruning to keep it narrow and dense. The only other option that comes to mind is to put in some type of wire fencing and plant an evergreen vine on it.
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