Re: Aluminum hull: removing reg numbers
3M Trim Adhesive Remover. Not a new product but works great. Don't have to wash off the WD-40 so ya don't have a big dust mess from the first trip down a gravel road to the lake too.
As Bond-O posted, do the big work with a hair dryer and a credit card first, then wipe off the leftover glue with whatever you choose.