Some of us can drive down the road, talk on cell phone, drive with our knees....some drive with white knuckles, looking straight ahead at 20 MPH, where a cat running out would make them flip the car..
I fly single pilot routinely at Fl450, working on a laptop, IPOD under the Bose glancing up to monitor things.....the biggest distraction is passengers wanting to talk...not what I bring to the table for entertainment....I will get up there and do partial panel, double reversion on the EFIS..work on flight plans and paperwork, maint. logs...read books....I can't even imagine the copilot being anything but someone I have to watch, monitor, as he reaches out and wiggles some knob.....
Seriously, if I had a copilot, I would WANT him to take a nap or read a book or go in back and pour drinks, not up front messing with stuff...