Not really a SMB area of the Charles. Tons of vegetation and its shallow. You'll need to walk around a lot to hit the shore points. Ive found the bridge to be too shallow of an area to hold anything good. The pier off Moody street has been good for others and you can use google maps to find a way to use the cemetery side for shore access.
The Moody st pier is now a Kayak rental area , not sure if you can fish there but renting a kayak is an option....