I would get rid of the trunk if there is no way for you to get him out if he is in there. You want to have access to him at a moments notice. Also if he can get in and you cant get to him what if he gets stuck? Bps love to squeeze into small spaces and i have heard stories of them getting stuck in hides such as the one you are describing. Also i have some that like to roam a bit in their tubs as I dont have hides and i have some that like to stay in the same corner and never move.