ouch. I'm on a 13 m796 with ABS. Even smaller tank than the non-abs. A bit disappointed with the capacity, but I can live with it as the bike is just ridiculously fun. My first bike SFV650 Gladius got about 55 mpg and I easily went 150 without the light coming on. I have the front sprocket change, only 800ish miles so I'm sure my MPG will change but currently getting around 45. sometimes only 43-44. My light comes on around 100-110 normally. I don't push it much more than 10-20 miles after that. I want to, but just don't want to take the same walk you did. LOL! How long until your light comes on?
I just got my carburetors rebuilt and tuned by an expert, and it made a huge difference. It's running smooth as silk, and my gas mileage went up from 42 to 44 mpg, to 55 to 58 mpg. These carbs had about 70K on them, and the emulsion tubes had gone pretty oval.