I set the wooden spacers up between the winsdhield bow and slider front bow, then carefully clamped the top front and back ready for the first holes. I measured about 20 times, then drilled and clecoed the slider to the back and front bows. I then measured the 1/2" either side for the next holes at the back, then 2" spacing for the remaining holes on the back and front bows, leaving at least 1" clearance along the bottom edge.
