In your situation I would probably go with the Verbos Multiple Envelope, I think the different outputs would complement the BIA very well and make it sound like more than a single voice. A lot of people associate it with the Varigate but it's not my style. Each Verbos module screams techno and later on you will find plenty of uses for the gate outs. You will also be able to feed the sequential switch with various outs. As of clock modulators, IDK, you could use the Maths to create gate delays or go with the Malekko quad delay (see Divkid video)? Maybe a burst generator would be cool, Ladik make an inexpensive one. But make sure you validate these with others, I far from excel at planning racks!