Alright, I've returned after much frustration to at least provide a bit of an update for folks that may be having the same problem; things I tried and how they ended up (and current progress)
Different USB configurations (the cheapest option)
Still using various USB type A cables that I had laying around; had not bought any new ones yet
Used mount-included cable, as well as other cables I had (4 total)
Going USB from mount directly to the Pi4 did not work, no matter the USB port nor the udev rules
Using the hub on the camera worked okay, but ultimately I still had some errors and it was still inconsistent; not really acceptable from a trust perspective
Tried udev rules for all of the above attempts; didn't make any difference unfortunately
Figured this would solve my woes, but this ended up leading to my previous post and immense frustration
This was going from mount (with new USB cable) -> powered hub -> Pi4 USB3 port
Updated udev rules to account for the new hub; didn't matter and was wildly inconsistent; usually manifested in random "read/write" errors on the logs, which would sometimes manifest as full-on timeout errors which would completely ruin any guiding / tracking and happened randomly
What ended up getting it working? A
stupid unpowered USB hub
that is actually currently connected to a USB 2.0 port on the Pi
No udev rules for the hub, only udev rules for the mount still in place; not sure if this matters or not at this point and will test to see how it behaves with no udev rules
USB setup here is mount (new USB cable) -> unpowered hub -> Pi4 USB2 port
I suspect this would also work on a USB3 port on the Pi4 but haven't tested this yet
Absolutely zero problems with read/write errors or timeout errors last night
HOWEVER as full disclosure, I ran into a lot of guiding calibration issues last night as well halfway through the session
I'm not sure if this is related though, so I would caution anyone away from thinking that the hub solved one problem but introduced another (I don't have enough info yet to be sure)
Something I am going to try is getting a
USB to RJ12 adapter
to go directly from the Pi4 to the HBX input on the mount and see if that also has good stability
Not super confident about this, but might as well try different things at this point to save other folks with these problems a lot of time and $$$