Not-As-Sloppy Joes: use hot dog buns!
Hate Sloppy Joes because they are so, well, sloppy? Use a hot dog bun instead of a hamburger bun. The top and bottom bun stay together, keeping the filling from spilling as easily. (This also works well for pulled pork or other messy sandwiches.)
For those of you not familiar with Sloppy Joes, here's a basic recipe.
(Anyone else grow up with those Lawry's spice packets? That was my Mom's "secret" for making enchiladas and spaghetti sauce.)
Related (because Sloppy Joes are camping food!): Family camping hack: Cook your first night's meal before you leave