When I was re-doing the bathroom, a number of floorboards were missing between the shower and the toilet . We have two toilets and everyone was under strict instructions not to use that toilet. The way to it was blocked off with one of those big, floppy buckets full of stuff.
Our eldest son was 10 then and very small and light for his age, he still managed to ignore instructions, climb over the bucket and fall through the plasterboard below. Fotunately he managed to grab on and not fall right through.
Don't trust pasterboard to hold anything!
SteveW