That would work, it would be something similar to what the Navy does to slow and prevent corrosion. To get an ideal how corrosion is actually going a zinc anode that is outside the hull and in contact with the water will give you a visual. Common ground to battery is good, then grounded to zinc - better. Now all this being said Navy ships are is salt water all of their lives, there are several anodes thru out the hull, changed when they are down to a certain size. Going that far with anti corrosion is not necessary for a small aluminum boat. But it doesn't hurt either. Good fresh water wash down is the best preventive. Aluminum when corroding will leave pits with a white powdery looking dust. Vinegar and a good primer and/or paint stops it. Where 2 unlike metals are in contact are usually where it happens first.
Overall the amount of corrosion you will get in your use will be almost nil. Yeah I know I went way to far on this, but I couldn't stop myself. The meds were wearing off this morning.
