We have several true cooler incubators, they are probably the best inc you can make for the money.
You will not need that much heat tape, ours have two 30 inch strips of flexwatt in them, a bathroom ceiling fan on the floor plugged into a rheostat and a herpstat thermostat.

The fans that come in these coolers run WAY too hot to use them and they do not circulate the airflow enough to maintain the correct temps top to bottom.
We tried the fan that comes built in to the cooler and had over 90 degrees in the incubator without using any heat tape