RICH,First of all, you can put the port anywhere you want as long as you have at least 2 inches for it. You can even put it in the front. Placement of the port is not really an issue except for the need of at least two inches.
Second, mine are about 6 inches from the walls. Unlike MINIATURE MUSIC(point source speakers), the array puts out a cylindrical wall of sound in the near field without much reflection at all. So, as far as I know, proximity to the wall is less of an issue, and six inches with the array angled to your seated position should be fine.
I await hearing from Thylantyr or Jim Griffin for the definitive answer.
Good luck on your project. You won't regret giving up MINIATURE MUSIC for the real thing,
Marlboro