No, I don't think that would work, because whatever is cast on at the end of the raglan increases (since you are knitting top down) would contribute to the width of the body. It won't make the armhole any longer, and length is what you need.
Keep in mind that if you are leaving this sleeveless, there will be no cap sleeve, so no bulkiness. If you do decide to make sleeves, maybe make them in stockinette to cut down on bulkiness.
Can't wait to see the final result, hope this helped.