Iris MCB-S Rack getting the proper ambient heat?

So i found a great deal for one of these for only $75.00. I figured i don't need it yet but it would be a shame to pass it up. Anyways, its belly heated. The snakes racks are in my room which is definitely not the proper ambient temp. On my other rack i just have two separate sets of heat tape and thermostats. What im wondering is how to add additional heat tape to this rack to create a good temp? Should i just put more heat tape on the belly side or back? Im really not sure what the best way to do it.