Have you seen my Molly-Mac-inspired pack, either here or over on Hammock Forums?
It might be what you're looking for, though it isn't the lightest option. It doesn't require anything but bar tacks and straight stitching, since you've got a set of shoulder straps and a waist belt already attached to the frame. It's really easy to do, once you get the timing of the sewing down.
Looking at the way that frame is designed, the simplest way I can see for putting things together would be to make a PALS array out of a doubled-over layer of nylon, draped over the top bar on the frame (sew the webbing to one side of the nylon before draping it), with four "keeper" loops (either webbing or grosgrain with velcro, side release buckles, or just sewn together if you don't want them removable), two over the middle crossbar and two over the lower crossbar, all bartacked to the side of the array facing your body (again, before actually putting the array on the frame). That should keep it from moving around when you're hiking, but you might wind up wanting to add a couple more loops to attach the array to the vertical frame supports.
It won't be SUL, but it should be really easy to use.