Well you can't control much of anything for certain in random maps. If you wanted to make a map in Galaxy Forge you could exactly place where everyone starts, assuming you set the "RandomizePositions" option to false. Also certain maps, like Razors Edge or many of the ones added in the new patch, do have teams either put right next to each other or apart. However, they're designed for even teams, not a 2 v 6, so I don't know how that would work out.
