DD used to do the EXACT same thing for her daytime nap at about the same age as your DD....she'd absolutely TRASH her room. But once it was trashed - what more could she honestly do? So I left it.

Something that has always worked for me is just going back into the bedroom say nothing, just put her back to bed, covers back over her and leave the room again (I'm a door shut mumma too). At the most I've had to go back in maybe two times maximum - she soon learn't she wouldn't win that game so she went to sleep first time from then on.

In the meantime (I know how annoying it can be cleaning up a trashed toddler room, especially when pregnant) I put locks on the drawers - but we've since taken them off, no trashing has occurred since!!

Good luck hun!