Years ago I would suggest a trash pump and in about a hour boat would be floating in slip. Not in these times though.
With boat secured in slip you might try "charging your batteries" with boat in forward gear
(forward less mud in intake)
When water is low better.
And if you have a clam rake you can stir up some bottom while you are claming of course. Or heard of garden hose tied to pole.
Can do little at a time.
Better if have powerboat friend with big motor
Whatever you move will go somewhere, not so good if ends up in fairway or neighbors slip. Not so bad if out of way near shore.
Thinking will not occur fines if not too obvious, but i do know a good bail bondsman.
Also if problems in spring ...does water level lower later in season?