A whole lot depends on the steepness/flatness of the ramp being used keep in mind. I have a '04 X2 on a tandem CA built trailer, and 98% of the ramps I have used I leave just a bit of the top leading edge of the trailer fender showing above the water, maybe an inch (see elipse in attached picture). The back end of the boat is usually barely floating... same with loading, the boat comes in, contacts the bunks, glides forward up to about a foot from my orange roller (replaced boat buddy), slap the winch stap on and power forward till it touches the roller, tighten winch strap, pull up ramp.
mzimme description of lining up a little ways out using power, neutral, power, neutral, just bumping for a second or two for steering ... seems to help with line up coming to the trailer and not coming in too hot either. My wife actually takes the boat both unloading & loading and I am in charge of the trailer.