A higher rise would help lengthen a shorter guy, as long as there is relative proportion to his physique. If said subject has a short torso, he might want to stay away from a high waist (but that is true of all folks with a short torso).
A high waist on an overweight man is a bit more tricky. I suppose it could work if attempted with a dark trouser and and full leg paired with a chunky shoe to anchor the body. It could also be a disaster if a light color trouser is worn which might draw attention to the lower abdomen area (isn't that called a fumpa?).
I think 12' is the perfect rise. High but not to high! Epaulet's trousers are a must : - )