Bella is 9kgs and in Huggies but she doesnt wet though touch wood! The only other thing I could suggest would be a Modern Cloth Nappy (MNC)Night time nappy - I am just looking into cloth myself so bear with me - they are a cloth nappy that has a really absorbant core of matterial especially fro night time - they are also made just like disposables so not like the old style cloth nappies - they are the same shape as dispoables just you wash then not throw them.
There are probably some night disposable ones out there - I have just heard form alot of the ladies on here with big night time wetters that MCN night nappies are great. There are also a few ladies on here that sell Night nappies so they can tell you more.
Hope that helps
Kate