Midi to host over Ethernet?

[Dark Waves]

Is it possible that the expander could be used to connect to USB host computer and run the Ethernet from it to the rack where the MRCC exists?

A Remote 7 expander can't connect to the PC, an MRCC has to do that; however, 2 MRCCs can be daisy chained, USB from PC to one MRCC, then ethernet cable to a second one or an expander, which would give a lot more distance.  Also, if the distances aren't too extreme, you can run a length from the PC to a USB hub, and from there to the USB of the MRCC, to double the max cable length for the USB run.