That's funny, I'm in the middle of doing almost the exact same thing right now too! I loved the olive green based tartan I found for my first kilts but the ones I made then had some "issues." Luckily I didn't know about cutting out the back side of the pleats at the time so the fabric was still intact enough that I'm combining the two 2.5 yard knife pleat kilts I made (yes, the extremely reduced yardage should've told me I wasn't doing it right) into a single 4 yard box pleat. Took 3 days to carefully "unstitch" all the machine-stitching I did on the two! Once I buy more matching thread I can finish it up and see if my experimental tartan recovery was a success too!