though vintage bib fronts stopped way above the pant line, this was because men either wore cummerbunds or a matched pique vest. since you wont be wearing either, I suggest the pique stop underneath the waistband of your pants. it looks odd seeing the end of the bib front peaking up above your waistband I will assume that the pique is being placed on top of the body of the shirt, and that it will not be backed with lining to stiffen the front. did you go with a voile body? are you putting pique on the outside of the collar and cuff?