Try the RIT and do it absolutely according to the directions. I have a plastic tub with handles that I can lift even with the liquid and garments in it. I do the hot water and such then sit and watch TV for a while and stir the stuff the whole time. It has always worked for me.
BUT the fibers of the garment will or won't take the dye according to what they are. 100% cotton takes color. Fabric that is poly/cotton? Only the cotton will take the color so you end up with weird looking results.
If it were me I'd just go buy new skirts or buy some navy fabric and cut some rectangles out, sew up the sides, turn down the waist, run some elastic, then hem them to her knees and be done.