One camera, one lens, one film - for a YEAR ? !
That's a toughie...
I think it would have to be my Leica 111b fitted with SCNOO rapidwinder and collapsible Summicron 50.
The 111b has just been serviced (for the second time in the 26 years of my ownership), so it's as smooth as silk, with excellent rangefinder contrast.
I've used it frequently for streetshooting, as it's small and inconspicuous and onlookers don't take it seriously, thinking it's a toy (!).
It's capable of quickfire shooting when needed, with the excellent SCNOO winder, and with SOOKY attachment fitted, capable of closeups, so those bases are covered.
Keeping my nine IXMOO's constantly loaded with HP5, and plenty more available in the freezer, I think I could exist quite happily for a year using just those tools.
I'll have to try it sometime.....