[No Pattern] Can you help me think out this alteration Sewing Machines Parts and Sales in Los Angeles

I bought a dress that I knew might be too big for me… I was going to just take in the dress at the side seams all the way up, and along the sleeves – I’ve done this with a few other dresses before, and it’s worked out great. But there’s a side zipper! Also a short zipper at the back to get your head through.

I was thinking of still putting in the side seams, then taking it to a tailor to put in a longer zipper in the back that would end at the waist band? There’s a seam that the back zipper is attached to that goes all the way from the top of the neck to the waist.

So extend the zipper all the way down the back seam to the waist:
http://www.forever21.com/images/f21/productdetailpage/zoom/back/00117121-02.jpg

Does that sound like it would work?