Not sure what you mean by ( fussy cutting) a strip 84" long? Are you isolating a specific design that runs the length of a fabric? If so I would probably first fold carefully the fabric into a manageable length and ( rough cut) a strip about 3-3 1/2" wide isolating the design. Then I would open the fabric and cut the strip as a single layer making sure it is lined up properly and cut it to the width I need.