I would consider holding off on the Batumi in this size case with both a clep and a maths, you can get even more related modulation putting the bi-polar output of clep through the rectifier of kinks (and provide attenuation through channel 2/3 of maths).
I would consider replacing the tip-top sampler with a disting mk4 or also getting rid of the roti and getting a disting ex.
Another module to consider besides the varigate would be the steppy (saves you 4HP)
ditching batumi and swapping steppy for the varigate gives you 14HP to work with you could pick up a matrix mixer such as u-he CVilization (tons of functionality packed in) and perhaps a LPG (the LXd matches great with BIA).
Overall I would plan on a bigger case, I picked up a Mantis and so glad I did because you are going to hit a wall and want to add a module without anywhere to put it.
It is your synth so don't be to concerned about getting it perfect, that's half the fun, but you have a ton of modulation in this case with only two voices imho.