I split the RCA audio output connector from a single tall wobbly one into two sturdier ones. I also moved the Raspberry Pi outline around a little bit so that the mounting holes fall within the board instead of outside of it. For now, I've decided that it doesn't matter if the Raspberry Pi's pin headers match up exactly with the ones on the Dexter board because this designed will require a ribbon cable regardless, so as long as they are close, it should be okay.
I've got quite a bit of space in the lower-left section of the board now. I am going to start bringing stuff down and packing it in. Switching from through-hole components to surface mount is going to shrink the board size down quite a bit (which is a good thing).
One component that is not on the board yet is an audio amplifier to make MACH 3 work. So I will need to leave some room for that, assuming we determine that we need one.