Hello lukethemore,
Have you considered Dual routing mode? The H90 would act as two independent stereo effects processors where In1 > Out 1&2 would be Path A and In 3 > Out 3&4 would be Path B. On a program basis, you can place both presets on Path A, both on B, or one on each. Plus, when they are both on the same path they can run in series or parallel.
This video gives an in depth explanation of Dual routing mode: https://youtu.be/0G_WtfUatSc
