Having done alterations on some fairly complex skirts in the past it can sometimes be more effective to alter the waist edge.

Sometimes just undoing a couple of seams and narrowing the waist will lift the garment to a more flattering height, making the wearer look thinner as well.

I have not been able to examine a Utilikilt closely, but know they have a 'fixed' waistline, so it might mean removing all or part of a waistband and maybe putting in a join or fold, but it coud be a better alternative to working on the hem edge.