First of all, a second VCO would probably be useful. One alone can sound a bit thin, but put two together and detune one slightly, and the sound gets real huge, real fast.
Consider replacing things that are large with the same things, but smaller. Such as: https://www.modulargrid.net/e/g-storm-electro-jp6-vcf or https://www.modulargrid.net/e/codex-modulex-%C2%B5motion . Keep in mind that in a restricted space such as this, you need to cram function in as best as you can, and the more functionality your build can have, the better. For instance, by doing those two replacements above, you then have room for the QCD's expander module, which really ups your clock modulation capabilities.
And speaking of clocking, given that you're dealing with two prebuilts that contain sequencing capabilities, you might want to look at modules that let you screw around with that aspect to a greater degree. In this case, I'm talking about Boolean logic, devices such as comparators and derivators, and gate/trigger delays. One example of this sort of function would be to use a comparator to fire off a gate when the Wogglebug's output crosses a certain voltage threshold, then feed that + a clock into an AND gate. That gate will then output a gate only when the comparator's and the clock's gates are both on; this is the sort of thing that can allow you to create a load of complex cross-rhythms between all of the parts of your patch setup...and potentially beyond, if you have other synths that can use those gate pulses.
One other thing that's lacking here is extra envelopes. Sure, the Maths can do those, but that's sort of like buying a Maserati then only using it to drive to the grocery store. Consider some sort of complex AR module, like Doepfer's A-143-1 or Sputnik's Quad Function & Trigger Source; with those, you can use the module as a bank of EGs, a complex function generator, or (in the case of the Doepfer) both at once. And this also dovetails with the clocking strategy above.
