I'm going to go out on a limb, here, and suggest a smaller sharp (not universal point) needle (if thread size is okay). Many years ago, when I sewed some denim jeans for my kid, I did the seams with a smaller needle for the seams and of course had to go larger for the top stitching. It worked really slick. Another thing that helped when got to a thick seam was to stitch up to almost the seam where the presser foot was starting to angle, was to stop and put something (folded cloth or cardboard) under the back of the presser foot so that the presser foot was parallel to the bed of the machine.and continue stitching. I now have a plastic piece like a Jean-a-ma-jig or hump jumper.
I thought the 201 would be good, too. I saw that someone did a pleated mask with a Rocketeer and didn't have any problems, nor did they raise the back of the presser foot.
Hope this helps. I haven't tried the pleated masks, yet. I've altered the masks that I have made to have a casing for either a stitched bias binding tie or a t-shirt cut 1" thick and stretched.
Janey - Neat people never make the exciting discoveries I do.