Have you read our article on the ZTL here?
http://www.visitflorence.com/tourist-info/driving-in-florence-ztl-zone.html
This is pretty updated to show that the area to the south of the Arno, particularly the area near Ponte Vecchio, is no longer a B zone but an O zone.
Doesn't matter anyway -- the three zones, A, B and O, are ALL part of the ZTL which only those with permits can access during the hours that the ZTL is active!
So assuming you are thinking of visiting during the day -- NO, don't try to park
that close to the center, you will enter the O zone (O stands for Oltrarno) and you will get fined.
Unless you are entering and parking after ZTL hours. Then you can enter and get closer - although not that close to Ponte Vecchio. There is a second camera (the one marked #26 on the map) that delimits a pedestrian only area - you can't enter that AT ALL during the night either (unless you have a permit for that area).
You don't mention WHEN you are coming to Florence -- because if you look at the map, you CAN drive along the Arno's south side DURING THE DAY in what is marked as sector F - so you CAN PARK along the ARNO in this area, which still brings you pretty close to Ponte Vecchio.
Remember it is PAID parking, so during the day, make sure to pay and get a ticket from a nearby parking meter that you put inside your car.
If any of this isn't clear, do post your questions --- I'd prefer to answer any doubts to ensure you enjoy a happy time in Florence, worry free from parking/ZTL problems
