Incubator question

I am building a new incubator and I picked up a rockstar display case pretty cheap and decided to turn it into an incubator.
My question is should I mount the heat tape on the back wall and if so can I tape it directly to the plastic inside shell of the fridge? Or should I make something for out of melamine and then mount the tape on it?
Thanks in advance

We converted an old upright freezer into an incubator. We ran 11" flexwatt heat tape down the back and taped it to the shell no problem. We drilled a hole in the back to run the extension cord to the thermostat then seal the hole with spray foam (great stuff). Oh and ran the heat tape all the way down the back. Hope this helps.