Genesis has a few dipolar/bipolar arrays that use a line of both rear and front facing dome tweeters but they are trying to maintain the dipolar effect above where the their big planar tweeter rolls off.

Frankly, I don't think that you need it. A single dome tweeter would not keep up with a line of tweeters on the front side--too much sensitivity different. You would need to dupicate the line on the front side of the box.

Bottom line is that a properly designed line array doesn't need a rear facing dome. I suggest that you focus on designing a good monopolar array. That would be enough to blow you away with spacey sound.

Jim