(This is assuming you aren't planning to show your underwear or torso to anyone.)
For now, I'm still using my male underwear (Snob boxers), and they work fine, mostly. I tuck, then I pull them up (UP, like, they almost reach my chest), and it mostly holds things well. Since there's a lot of "surface", it just can't slip out. The only issue is that it tends to go down with my pants, which have that nasty habit because I don't have enough hips for them, but then, a discreet (or not) pull does the job. And if I don't do it too hastily, it can hold on even when I run.
The cool thing is that since this underwear covers a large surface, even if the tucking doesn't hold, it doesn't make anything visible (or hardly so); everything stays downwards/backwards, just not tightly. That's because this model doesn't have a "pocket" in the front for the parts. Since there's no extra room in the front, the parts don't tend to go there.