Okay, so, from what I've read the top issue with tucking is that once you put your things away, they have a tendency to escape, so it takes some creative problem-solving to keep them inside.
The problem I've been having isn't that they come out, since they can't do that if they never go in! According to all these lovely diagrams, the inguinal canals go upwards and outwards, but the only place I can place the testes (well, right testicle, since there's no room for the left one after the right one goes there) is directly above the penis, but that doesn't seem right since it creates a large bulge and I'm preeettty sure the whole point of tucking is to reduce bulging.
I know there was another person who was having this issue, but they self-solved their issue fairly quickly so I couldn't quite get a good idea of what they were doing...
Sorry, and thanks~!