Does anybody have any suggestions for the middle I/O board in an Astro Pi?
The real ones have a custom board so I am looking for something that can provide similar functionality - mainly a real time clock and GPIO pin access for the buttons and infrared presence sensor. One possibility is the Expander Pi from AB Electronics, but the I/O on this is via an MCP23017 expander, rather than direct, and the pinout puts the connections in a fairly inconvenient position within the flight case. There is no room for right angle pins, so wires would have to be soldered directly and there is only a small gap for them between the case wall and the sense hat standoffs. There is also no slot in this board for the camera ribbon connector, so routing that would need to take it over the USB ports. Having said all that, it is the most promising candidate I have found so far.
Astro Pi 2 with Expander Pi
I also considered using a GPIO splitter and one of the very small RTC boards you can get, but this runs into collision problems: the sideways pins hit one of the two buttons, and the RTC sits where the IR detector should go.
Astro Pi 2 with GeeekPi 1 to 2 GPIO splitter and Adafruit PiRTC
Has anybody tried any other possibility which can they recommend (or warn against)?