I have a new but similar setup, this time a little bit larger, one full red belt of plastic. The save requires both the Aligned Underground Pipes and Flow Control mods. https://drive.google.com/file/d/1lRkmPW_KGTDdtmXk3gafRnQpRH1G2nAx/view?usp=sharing
When running full speed, the setup seems to do well. My issue is sulfur production without plastic production. When not running the factory for science packs, I will the need to produce sulfur for sulfuric acid and/or lubricant, without plastic production... like when expanding/upgrading and producing blue logistics stuff... what to do with the excess polypropylene? It can not be burned or vented, yet it is required to produce for the hydrogen sulfide.
The reverse (plastic without sulfur), can be handled by simply venting the excess hydrogen sulfide.