I forgot to mention, that I also roll down the back of the diaper (or front if they are belly sleepers) which seems to stop the leaks also. This way it can't wick out the back. And Huggies Supreme have an elastic waist in the back which would probably help. Mine are both belly sleepers, so I roll down the front of their diaper.
Also, when I was having alot of problems, I called Huggies and they said the overnights are equivalent to the next size up in the regular diapers. They just charge more for them!
HTH