Turtleneck is not usually recomended for short/stout necks. But there are some new designs that are out in the market that can just be for you. For one thing, haltered designs will help to elongate the torso.
The problem most short necked people have is being short in stature. For the stout necks, these girls usually have a box figure. The cut of the clothes is very important in altering the shape. Part of the cut is the neckline. Necklines are tricky because they are the top of your garment. If you are not comfotable with the haltered effect, find ones that are semi-haltered. The opening of the armhole starts one inch from neckline. This hides the underarm forld that most full-figured women wish to conceal.
In buying turtleneck tops, find ones with shirring. These shirring creates lines that will elongate your torso. A keyhole or cut-out design will also do the desired effect. These two elements will go a long way in adding to your neck length.