Have you tried just using folded flannels as inserts?.
This is what we're doing - we actually bought a job lot of 'super absorbant cloths' from Costco the other week and I use those in MamaTieDye's home made nappies for night time with the equivalent of 3 folded up cloths inside. And on top, regardless of whether she has ended up in a padded daytime nappy or a pretty MamaTieDye one, she has Boots plastic nappy pants on top. Because she's a heavy wetter.
Daytime, Daisy has the Tots bots all in one thingummies. With at least 3 fleece boosters!