the heat produced has to go somewhere... it does not change. blocking off the exits so to speak may provide some comfort for you, but at a point of what does it do to the components inside the barier that you have made?
meaning, you are containing and attempting, to redirect air, in a manner that was contrary to the original design. all well and good for your shins, but in reality, if the originator, or anyone else creating barriers for flow of hot air, has the credentials, time spent on temp rise, life cycle heat cool statistics, and longevity of components in "the oven", might wanna let it be as is.
do you know just how hard it is to make a "BETTER" mousetrap?.... define better....