Hi Dario.
Yes, being inverting or not inverting is not important... the problem is the same on either conditions. I think this is not a valid solution so we need to think to use a three state driver to allow boards that are not transmitting to detach from the bus.
I'm thinking to something that generates the three-state enable signal without requiring a dedicated pin on the board. Let's imagine to generate a carrier trailer on modulated signal: we can integrate the modulated signal with a "simple" RC circuit used to enable a three state driver. The RC could be driven by a diode connected to the gate of the driver. As soon as the trailer is detected, the enable signal is generated. As soon as the modulated signal stops, the enable signal falls down and disables the output buffer.
We can try to understand what's the minimum RC time required to have a working solution without affecting too much on the data transfer... Adding a Schmitt trigger will probably enhance the performances...
About the coil, unfortunately I don't have any experience on that... so probably the best option is to ask to the Community or setup a test-bench.
I plan to use a normal SMD coil made on a ferrite core.
Thanks!
Marco Signorini.