I trimmed the windshield on my bike last night and all went well. I read the article you linked to and used some of their tips. I used a dry erase marker on the windshield and drew a line right across it and then went for a ride. After a few new lines I had the one that was right. I have it set so I can see over it comfortably by about an inch when I am on the highway. You look at different heights in different riding situations, further ahead on the highway(higher) and closer in town(lower). You should factor in where you do most of your ridding and cut where it is comfortable and where you will be looking the most. I taped up the outside the window about 3" either side of where I wanted to cut and retraced the line onto the tape. Using a fine jigsaw blade I cut as straight and slow as I could. I then used a piece of 3/8" plywood about 2"x4" and wrapped 320 grit sand paper on it and ran it flat on the length of the cut to even out the highs and lows. Once it was all even, I used the same sandpaper by hand to put a radius on the new cut to match the orig. part of the windshield.