You could do something like that. I'd use the midhorn, tweeter and crossover as shown in the seven π plans. The woofer needs to be within a couple feet (front to back) of the midhorn for proper summing, which is fairly easy. Spacing between midhorn and tweeter is more critical, but the design is optimized so that they sum perfectly when the mouths are flush. That arrangement makes both acoustics and aesthetics very nice.
seven π cornerhorn loudspeaker