I thought some more about how going to two boards might work layout-wise. My first thought was that it would be very undesirable to go to two boards, as we take up stack space which could be allocated to other experiments. With conservative planning on the flight board and some work to limit excess components on the current design, I think it's entirely possible to fit the flight model on one board. 

Looking at the board space we have available (~26 in^2) and the current schematic, there would be several steps I would take before going to another board. First, we have a lot of bottom board space which isn't used at all. Pullup resistors on the digital side, power supplies, and even the CPU could be placed on the bottom of the board. Just by removing the UFL connectors and replacing the 0603 components with 0402s, we'd save around an inch for practically nothing. Additionally, more layers on the board may allow greater route density on the top and bottom layers. I think that 8 or 10 at maximum will be sufficient and provide a shorter path than a second board would allow. I made an approximate placement diagram which shows the current configuration and possibilities for the new board.  

I'm not opposed to multiple boards for development purposes. We could break all the circuits out onto different test platforms which could be distributed to more people for software development. We could troubleshoot each section individually before combining onto the flight model. I think for the best performance on the flight model, it should be a single board. 

Something Bill pointed out in the meeting was that heat dissipation might become an issue with so many components packed onto the board. While the board can do a lot to sink heat, perhaps additional sinking will be necessary. On the RT-IHU, we plan to create a heat spreader which presses a ceramic block onto the TMS570. Originally, this was going to also have milled cavities to act as shielding for the components, but the design was shrunk for unknown reasons (something that Bob Davis had been working on). Perhaps something like this might be beneficial, although it would be expensive and add weight and height. Just a thought. 

This is my point of view from the layout side. While a challenge, I definitely think a single board is possible. Thoughts?