A dealership I worked for used this stuff to remove spray painted graffiti the kids would spray on the cars from time to time. So I doubt it would have any trouble with latex paint.
Clay it....Or try this pink wax called liquid Luster...It took a gang bangers tagging in oil based paint marker off my hood on my neglected paint on my Integra after it sat on there over night....Its the **** you see at car shows where he spray paints the hood then removes it 1-2-3-. It worked wonders for me...try it!