I don't connect devices to calibre, that's far too elaborate for my simple needs. I drag files I want onto the device and delete them from the device when I'm done with them.
The main reason I have the cables is so I can turn off the data lines when charging devices at places I don't trust (e.g. airports, cafes, telephone boxes etc), saves carrying multiple cables.
No idea if it would work with a Kobo attached to calibre, just buy a cable and try it. Any decent electronics components outlet will have them - make sure you get the ones that switch the data and power lines - some only switch the power lines and drop the data lines. Shouldn't have to pay more than USD5.00.
David could try one of these from Core Logic ==>>
USB Extension Cable with Data/Charge Sync Switch Australia
BR