What about wearing crop tops with high waisted pants just above your belly button? I know that it is suboptimal as bare midriff looks best with low rised pants but as you want to hide your outie to avoid excessive interest of people around you. Pairing high waisted pants or skirt with very short crop top would allow you to show few inches of your abdomen without intrugiung people with your belly button :D
Another option but more risky would be wearing very low waisted pants so hipbones are visible and pairing them with a shirt or sweater reaching slightly below your belly button. In my opinion this option looks better visually as I prefer bare lower belly to bare upper belly but there is risk involved as if your shirt raise too much because e.g. you lift your arms overhead your outie will show. You may try wearing sth that is not lifting easily as you raise your arms. For example you may try long loose tshirt knotted a little below your navel.
