I am not sure how heavily Bea wets, but I have found 2 P'tit Dessous bamboo inserts and a MF cloth on top works well in her hemp/terry stuffie, and if you need more room to add extra, there is lots of space left as they seem pretty slim (well, for a night nappy LOL)? Does make for a heavy nappy though, and my problem is of a different kind - Bea is starting to really complain about her night nappies when I put them on, unless it's the Wonderoo. She is constantly pulling at them and trying to get them off these days, and I've resorted to the odd disp at night also. Occasionally she leaks out of a disp, but not often - maybe that means she is not such a heavy wetter?
Anyway, hope you can sort it out!