That is a great effect. It looks like your stairs just dump right into the Sarlacc pit!
Excellent!
If you still remember the carpet underneath, an old trick would be to cut out the stained area, take it into the room and lay it over a piece of carpet under your seating area, cut out a patch the same size and swap them (replace the seating to hide it.)
Whenever I had to do this in the past, it was usually the closet that got to donate carpet. Make sure the knap is the same direction on both.
The other things is, have you considered just painting the carpet to look like the Sarlacc, now that you have a good scale and reference?
Great idea, I love the way it turned out!!