Okay, so, I've been looking though all of your feedback and changing a few things, now this is what I ended up with:
First off, you're probably right about getting a bigger case even though I wasn't a fan of it at first. I've known about the Mantis beforehand - a friend of mine owns one, and for some reason I've found it to be a bit clunky and, as stupid as it sounds, somewhat ugly, so that's why I didn't want to get one. @sacguy71 's other suggestion of simply getting the Intellijel 7U case is probably the most obvious solution, so that might be what I'm going to do. That also allows me to keep the Midi 1U module which I'll be relying a lot on and saves me space for a bigger 3U 5-pin Midi in module (and since the case is bigger I can keep the stupid music box in for now). Other than that, I love most of @Chace 's changes, so I integrated a lot of that, pretty much only changing the 4X Stereo Mix for a PanMix, since I've got more space to work with now. Added a spring reverb, since that sounds like it could be fun, changed the CIP for a Loquelic Iteritas and stuck in a Maths, because if I got the space, why wouldn't I.
If there's anything else you think could/needs to be changed or added, I'm always happy about suggestions. For now, many thanks to all of you for helping me out!