Hi there,
i tried to inflate satcontrol.img.zip with 2 different programs with GUI on a linux computer, both failed. Inflating on the commandline resulted in a file >5Gb. I copied it to the card anyway using dd , but it wouldn't boot. Downloaded it to my laptop and tried there successfully. It also resulted in a file >5Gb, but dd copied it and it would boot. Something is wrong with the file, i should say.
Anyway, good job! Been trying to run my own installation on a 3b+ over the last few days and failed (audio device underruns) or had a huge cpu-load >78%. So your optimizations, if any , do the trick. Load only abt. 40%. Keep on!
Martin