mini frig incubator.where to put the heat tape?

im building a incubator out of a mini frig and was wondering what is the best place to put the heat tape

On the inside ;) haha. I would put it along the back wall, with your fan at the bottom.

I put mine on the back wall, that way the heat isn't directly on top of or under and eggs. But def on the inside as mentioned above :D.

As others have stated, on the back wall.