This is one of the possum houses under construction.

In the picture, the back wall is facing us.

The big hole is an emergency access hole - it's there just in case there was an emergency, because getting into the possum house via the "front door", if you're not a possum, might involve dislocating something as you negotiate the sudden sharp turn at the end of the corridor.

Here's a simple top-down line drawing of the layout of the house.

The entrance corridor is on the left, the sleeping chamber is on the right.

The back wall is at the top of the diagram.

As it shows, there's not a lot of room for manoeuvring, unless you're a possum, then it's great.

Hmm... A thumping great hole in the back of a possum house.

What possible other use could it be put to?

Perhaps the panel could be removed, and it could be fitted with a frame, with flyscreen (it makes it darker, inside), and possibly some kind of fixed louvres or similar wooden slats, set to an angle of about 45 degrees, allowing airflow, but minimising the amount of light getting in.

It's an idea, it's a thought, it could possibly become a plan...

It's a win-win. She gets a cooler house, and I get to amuse myself by drawing plans and making things for her.