Thanks to Chantel for this Frugal Baby Tip!
Ooh, I still say, "Don't tuck everything in!" We use DiapeRap and I diaper messy -- I leave the edges of the diaper hanging out the legholes to form a better seal... We don't get messy covers! Yes, it's not a pretty diaper, but it works! It also makes the cover fit more snugly around slender legs.
Larger legs require a larger cover size. We don't get urine leaks (except for the occasional time we don't get the diaper changed as we usually would) because I don't leave a whole lot of diaper out and because we change regularly. What regularly means depends on your baby, the quality of diaper you're using, and if you are using a doubler for absorbency.