A agree with the above.. what I would do is talk to the bike seller and ask "Knowing I am large are you going to warranty this bike?" .. if they are willing to risk the warranty issues that is a vote of confidence. You don't have to give them your weight number (even though you just gave it to the whole world), but you may want to admit you are over the advertised weight limit.
The highest weight limit I have seen on a single passenger bike is on the Surly "Big Dummy" (they are naming the bike, not the rider). That is a cargo bike though and they may be expecting the weight to be distributed more. Speaking of Surly, you might appreciate the big squishy tires on their Pugsley.