Running steroids at a high body fat percentage is not a good idea. ALL steroids negatively impact cholesterol and blood pressure. Which probably aren't great to begin with if you are at a very high body fat percentage.
Not only that, running a steroid cycle at a high body fat percentage is going to put a lot of stress on your body and organs. It is also counterproductive because the higher your body fat percentage, the more testosterone will aromatize into estrogen.