I ran across this video on YouTube last night, interesting work you are doing there. I am (im)patiently awaiting my uBITX with the same goal of creating a self-contained JT9/FT8 rig. Have you considered adding a GPS module to the Raspberry Pi for time synchronization "in the field"?
-- Best 73 KD8CEC / Ph.D ian lee kd8cec@... (my blog)