Crochet steek and zipper advice?

The Fishtrap Aran knitting is complete (huzzah!), and the garment is reclining damply on the living room floor. No pictures, alas, as we Portlanders are wallowing in our February rain puddles under our lowery skies and the light is useless for photography. Now for the front steek and the zipper insertion. I'm using the crochet steek method, which worked handily on the arm holes, but it leaves a small roll of fabric at the cut edge. Has anyone attempted to sew a zipper to an edge like this? I'm in a muddle as to whether to sew into the roll itself, or sort of behind it. I might use a thinner yarn for the crocheting, which in theory should make the roll less bulky. And I'll be hand sewing the zipper, if that affects your advice. Thanks! I'm off to finish a BSJ in the meantime.