Don't forget, though, that you'll be sanding most of it off, so you won't really be adding all that much weight. By the time you fair the surface you should be just above the glass. You just need to add enough so that you have enough material to remove to reach that point. If you don't have enough material, you'll sand into the weave.

If you sand into the weave the varnish will take away the white color, and at first it will look flat and level, but as the varnish continues to shrink as it cures you'll see the weave telegraphing through the varnish.

Do it just like automotive finishes. Sand until you expose all of the high spots, then add more epoxy and do it over and over until the low spots are as high as the high spots.

BUT- like Etienne said, there are degrees of fussiness. What's yours?

m