This isn't meant as criticism and I hope you don't take it as such but you may be overthinking this. I don't think you have to tailor your answers to appear disabled but if you think it would help I would see nothing wrong in that unless you just have rigid standards and you feel your actions would imperil your self respect. I don't think you need to deceive or manipulate to ensure a good result from this test. If I was in your position I wouldn't hesitate to do so. I'm sorry but my mind is very foggy today and I am not sure if you consider this as a moral dilemma or a practical one.