I have printed many single walled items using S3D. You simply change the outer perimeter shell to 1.

I think the issue is more the model and hardware combination than the slicer. The model was created with a thicker wall than your nozzle so the slicer is just filling in what it thinks is the total model. If I slice the model linked in S3D with a .4, it wants to do two shells. If I punch in a .8mm nozzle, it does just one shell.