Sara you nut bar,
Have another look at the Wiki article for tucking and taping. There is a section on tape less alternatives. Believe me they work. If you wore the gaff as shown there would be no way that an errant stiffness 🙂 would show.
To elaborate a little. Once you have tucked the testes up and out of the way grab the empty scrotum from behind and pull it between the legs. Then take the penis and pull it between the legs and up between the butt cheeks and using the other hand, spread the butt cheeks to grip the penis, then pull up the gaff, fixing everything in place. Done...
Steph