That was another question I had. I read that the more space there is on the hive, the more the bees have to work to keep it warm, so I was wondering if I could switch them out as needed too. I'm really looking forward to all of the experimentation possible with beekeeping
Bees heat the cluster, not the hive.
The larger the space, the more heat the bees will need to generate in order to keep the cluster at the right temp. The interior hive body temp will not be as warm as the inside of the cluster. Heat is lost as it travels out of the cluster into the open cooler air inside the hive.