Does the crash happen even if you're not guiding? I am now testing with ASI178C and ASI120M. The 120m is running in a loop in the guide module capturing once a second, while the 178 is capturing 30 seconds. I even limited the OS RAM to 2GB and only 1 CPU.. it's still running without issues after 79/100 exposures.
I'd say test with one camera only (nothing else is connected), then two with the 120m..etc. then add the mount..etc. We need to find out what causes it to crash .
My general experience is that if I only take darks and flats with just the main camera in operation, I see no crashes.
It mainly occurs when running a real session with guiding.
I have not tried imaging without guiding, but I can try to carry out the steps you suggest next clear night. It may be a while though. Weather forecast is not good...
But meanwhile I can try out as much as I can inside.
BTW. Yesterday evening I had 5 consecutive crashes. They all occurred after the second or third image had been downloaded.
On the sixt attempt everything worked very well, and I could gaher about 5 hours of data.
I had problems with RAM and FITSviewer... So I did:
a) install Zram
b) disable Fitsviewer from options ( you may disable after check the first captured image )
c) disable some programmes like TEAMVIEWER ( is running by default in Stellarmate), to achieve more free memory...
In this case, everything runs in raspberry pi 3 ( only some randomly crash) from my laptop only use VNC viewer to supervise and control all stuff...
Another option is to use kstars on my laptop ( ubuntu 18.04), so with 8 G RAM fitsviewer never crashes. But I prefer that all runs in the raspberry to prevent some communications interrupts...
good luck with this fantastic environment... (only needs some debug and improvement )
The result seems to be that scenario 1 and 2 works nice. But when the mount is connected, the trouble starts.
For scenario 3 and 4 (when mount is tracking), I experience crash after just one to two images. I also saw one crash during plate solve.
So whether or not autoguiding does not seem to matter. Mount in operation seems to be a clue.
I take images using an ASI1600MM-C Pro with an ASI EFW (5 slots) while guiding with an ASI120MC-S all on a SkyWatcher EQ6-R which is connected via an EQDir cable and have never experienced any crashes. Having said that, I use a kodlix mini-pc which has 4 gb of ram and not an rpi. Also I have the FITS viewer disabled whilst imaging.
ASI6200 and filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro
ASI1600MM-Pro Cooled and filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R