Hi andio,
I have not tested yet, and that sounds be the easier way, but you should manually have the COM port created, attached and ready with the target before to open the serial port. We cannot simulate the btspp protocol in this way, because you give the target address and the service number, that is because I said to create a kind of router.
If you are going to check this right now, could please you post your results? :)
Best regards,
Jose