After the layup was cured, I washed with soap & water to get rid of the amine blush, then wiped with acetone. I only sanded off the high points, then washed and wiped with acetone again before troweling in the fairing compound.
Next time I do a layup, I try your method. I know a green resin will provide a chemical bonding to the next layer (which is how I applied the 4 layers to the keel). I just never thought of doing it between the last layer of the layup and the fairing compound.