Re: Need some help and advice......
Just a thought - I don't know the specifics of your carb's fuel intake, but you could buy a motorcycle or moped gas tank off ebay (or craigslist etc) and mount it on your top tube (in front of your seat).
This would give you plenty of fuel capacity, and allow you to completely do away with the tiny gas tank you currently have. From the picture you posted, it looks like a top-tube-mounted gastank would be higher than the level of your current tank, so flow wouldn't be an issue.
Motorized bicycles tend to get somewhere between 90 to 150 mpg, so if you're commuting 60 miles roundtrip, then you could use something in excess of a gallon capacity just to be on the safe side.