I've been double IC for a few years now and have learned a few things about leaks and adult briefs. Even if I point my penis down into the diaper when I move around some a and especially lean over, my penis changes position. It changes position for many pen if it gets hard and points out of the garment - often at night. The point is that for those who flood their adult briefs, when the penis isn't pointed down, there can be leaks. I don't side sleep but side sleepers have this issue certainly.
I have started wearing a very thin mesh bikini under the diaper which keeps my penis faces down at all times no matter how I move. It also inhibits erections. This means no more leaks!!!!!
I have also sometimes worn net pants under the brief and in contact with my skin in order to make the brief more comfortable esp on the thighs where I have redness and rashes from full time pad use. Basically you just pee through the net pants. FOr those who are bowel IC like me also, you can use an insert between your perineum and the net pants.