as they are nocturnal, it maybe worth your while to get some normal plastic shopping bags and put them down along the edges of the room, so that you can hear the snake moving if the bp comes out of hiding, stay awake all night in the dark or just have very dim lights on, have a torch to hand.
then once the snake comes out and start moving along the edge of the room and comes across the bags, the bags will make a noise, immediately put the torch on and shine it in that area and hopefully you will get your snake back safe and sound