I know this sounds gross, but next time you use a night napp., boostered or not.. weigh the nappy before it goes, and then weigh it wet in the morning. I think you need to find out how much your bab is peeing before you can determine whast nappy and how much boosting you need to use. Obviously evaporation does occur even with PUL.. but its only a few ml.. not hundreds!
If you can find this out, I'm very sure I can make you a set of boosters that can take a nights worth of wee. Its a useful thing to know anyway. I made my two testers weigh all the nappies before and after use for a few weeks when I was testing my nappies and different farbics out. If she wets through a paricular spot..or its wet all over... how she sleeps, side front or back, all these things are useful in making a specific item.
Totally agree about the nappies such as minkis's .. maybelooking at something a bit more practical and heavy duty instead of pretty for night time? Egyptian cotton terry is very very thick, and incredibly absorbant
Think about the heaviest bath towel you have and .. imagine it as a nappy, then add a cosy thick layer of fleece mmmmm!!!