I would remove the Neutron from the case as first step as it takes way too much valuable HP.
You don't really need it.
Next step is you need support utilities and modulation sources like LFOs, attenuator/attenuverters, mults and logic. Adding something like a Batumi or Divkid 0chd would give you a good modulation start and something like Mutable Instruments Shades or Noise Engineering Lapsus Os would provide attenuators and maybe throw in a Kinks and Links for support modules.
Next thing: how are you sequencing the rack? Maybe get a basic step sequencer if you want to create beats either in case or external like a Korg SQ-1 or Arturia Keystep with CV control. A good in rack basic sequencer and clock that I love is Pamela's New Workout as it small, powerful, easy to use and does a ton of cool stuff.
Third- function generator like Maths or Quadrax would give you lots of options or maybe Zadar.
Last- effects, a delay and reverb would add a lot to your setup. You can get something like an Erica Synths Pico DSP or Happy Nerding FX Aid.