well ,my bottle's just in a cupboard under the sink,but it sits in a well and has a dropout hole.having a sealed cupboard is best practice, but i'm happy with the arrangement.
in case anyone reading this is wondering- butane gas,propane gas or lpg are all heavier than air,and like water,if there's a leak, a puddle forms .if it's not contained in some way,it'll spread all over the van,like water. so having it caught in a well,then having a hole in the floor for it to drop out,just makes sense