Powered USB hubs is not a Solution (at least not for me on location).
In the studio it will work but on location it's useless because often there simply is no power.
For the workshops I'm experimenting with windows 8.1 and miracast. Keeping a sony duo13 close to me and sending the images to the display(s) via miracast.
I'm not using USB3 but I had lots of trouble using 30' usb active extensions on a MBP. Never any problems on a PC laptop.
I've found I can only get a reliable connection when using the first usb port on the MBP..that is the one closest to the front of the computer. Also I discard the active extension at the first sign of connection errors. The seem to go bad after 6 months or so of hard use.