I'm just surprised that you find it worse than the USB cable connection. You lock your doors (and reboot the system) every time you get out of the car, right? The OTTOCAST unit will need a few seconds to boot up after power starts to flow to the USB port.The usb cable works pretty well. It's just not convenient, not to mention that by using the wireless tray by Silent Cilantro (which is stuck at the italian customs btw), it's just not an option since the central usb is not suitable for CarPlay. Or maybe I'm missing some alternative option?
One thought: did you happen to disable the Bluetooth and/or Wireless functions in the car when you were struggling with the wired connection?