minimum spacing distance for white oleanders?

Garden Experts:
Please help...
To build a DENSE privacy screen, I am putting some white Oleanders (Sister Agnes) parallel to my street curb. I will keep them about 6 ~ 8 feet tall.
- What's the minimum distance between each pair? - What's the minimum distance from the street curb (without sidewalk)?
<PS> I don't care about the blooms, but do care about the foliage to block out views from top to bottom. What will happen if the bushes are put too close together? Will it reduce foliage severely? Will one bush fight/kill the other?

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