fireplace mantel and heat deflector

[stevo wis]

Hi Folks,

We have a woodburning fireplace that we use as our primary heat that does heat the stone quite a bit above it. I would like to add a rustic wooden mantel above it and then mount a big tv. I have attached a photo with a cardboard template.
The fireplace minimums from the hearth mantel is 54" to bottom of mantel, but a little lower would be better. Also we need to keep the temperature above the mantel low to protect the tv. My thoughts are to have my buddy bend a piece of steel that is the width and depth of the mantel and bend the front edge up 45 degrees that could deflect the heat to pass the front of the mantel. I would install this with a 1/2 to 1" gap below the mantel as an air gap. There is not much commercially available except cement mantels at $1500+. What do you think of this idea?

Any suggestions?

thanks,
Stevo