When the heat flow trough the material reaches equilibrium, the back will radiate exactly as much heat as the front side receives. At that point the heat shield serves no purpose.
If the heat shield is where most of the delta T goes, it will definitely serve a purpose. The corona normally drops off as it goes off into space, but if you can concentrate most of that drop in one place, then your electronics will be much happier.
[0] https://www.electronics-cooling.com/1997/09/one-dimensional-...