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
• Bought a new, higher quality USB cable
  • This didn't work; still having connection issues directly to Pi4 on all ports as well, same with ZWO CCD camera USB hub
• Bought a powered USB hub and even a fancy dovetail-compatible bracket for it
  • 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 $$$