No, not just the band. *Everything from the hip up* has to be big enough to slide over your hips. So the pant has to be cut straight, up from the hip. If there is enough seam allowance, maybe a zipper can be put in the side or back.

I don't know about any pattern changing, but if you're afraid the zipper won't turn out looking right, don't be. I made pants just like these several years ago and they came out perfect. I marked the seams and took my time. You may want to baste the zipper. Sewing's a learning experience and allows you to be creative, to do things you've never thought possible. Besides, there's not enough fabric in these pants for elastic; you wouldn't be able to get them on.

I have several pair of slacks that I have modified to exclude a front zipper. I put a dab of elastic in the waistband at the two side seams I then removed the zipper and pinned and sewed the front seam evenly. Take the hooks off the waistband and sew it together with it flat and unfolded. I then resewed the waistband to the pant fronts, turned it in and hand stitched it on the inside. The elastic allows me to carefully pull the pants into place.

HTH!

Blessings,

J