Lightroom: How I erase portions of the graduated filter

I love the graduated filter tool in Lightroom. With it, you can just drag a ‘window shade’ of saturation down over your sky or let in a diagonal leak of light in the corner of your photo. I was disappointed that the new version of Lightroom (LR3) didn’t add the ability of erasing portions of the filter. For example in the image below, I wanted to drag a grad filter of bumped up saturation and vibrance (for the blue), clarity and contrast (for the clouds) and lowered brightness for the overall drama of the sky. All well and good for the sky. But now, the boat is also darker, higher clarity and more saturated than I want it to be.

The way I go about ‘erasing’ this effect from the boat is to use the adjustment brush . Remember that with the grad filter, I bumped UP the saturation, vibrance, contrast and clarity and DOWN the brightness. So I will customise a brush with the opposite effects. One with LOWER saturation, vibrance, contrast and clarity and UP brightness. This brings about an erasing effect by doing the opposite of what I set the filter to do. And this is my result: