I ride a regular route into Central London most days and 3 days amounts to 150 miles (50% in heavy traffic) before I fill up, which is usually about 17.5 lts. This week I did a few detours and the fuel gauge was flashing red, milage range went down to zero and I took a chance an rode to my normal filling station. Trip meter was on 175 miles Bike still only took 18.5 lts so I think you can probably squeeze a few more miles out before you totally run dry...
Well yes, but it is also possible to run out completely just before you get to the petrol station. Don't ask how I know this.
I ran out of fuel twice with my Triumph in the 60s. Both times I was able to pull the clutch in and coast into a fuel station - lucky or what???
My 1200Enduro has a tank larger then 32.34litres as that is what I've managed to squeeze into it so far. Will try again to run it nearly dry on my next bout of riding, range in excess of 326miles came up once filled.