For a Rhino, I believe you have to be pulling at least 90 pounds if not 100. Speed is only have of what you need for penetration. You also have to have an arrow the weighs somewhere around 600-800 grains to get the penetration that is desired.
Lemme tell ya, you could spend a lot of money over there! I was after specific animals and didn't get a single one of them so it was a 'cheap' trip. NOT!! LOL!! The blesbok was one I wanted last time and didn't ever get a shot at. Got to stalk him.