After trimming the edges, I realized I didn't really need to add anything more, except a pumpkin vine with pumpkins made from bullion knots:
I then backed it with some great shimmery orange silk, quilted around the cross stitch pumpkin and tied the two layers together:
Binding the edges with a slip stitch seemed too neat and boring, so I used crude embroidery stitches to hold the binding in place. The result:
It's quite satisfying to have finished this well in time for Halloween.