Or.....paint it the same as the ceiling and it will appear as if it is part of the ceiling. I agree with kelleg for my second choice. A very thin liner. Side story: Things happen. We redid our backsplash because my first choice looked horrible. The installation was perfect. So, when our same contractor came back to do it a second time, I expected it to look the same. Different subway tile, but same plan. I wound up with slivers in the corners! I was told that in this installation it was un avoidable. Mmmmm. Anyway, I put my Keurig in the corner and it is now a non issue. Let us know what you decide. Beautiful tile! And, the fact that you did it yourself is amazing. Question Joseph. Should Tiber have started from the top and go down? That way if there is an issue it would be hidden behind the molding?

The radiation (radiant heat in the infrared) spreads out like light (because it is light), but this only falls as 1/R^2 when it is emitted from a point source. Other shapes only approach this at a significant distance. There are whole pages of thermal transfer functions applicable to one shape transferring heat by radiation to another nearby shape. But I get your intent. The heat flux density is higher closer to the gas flame, due both to more concentrated radiation, and to convection from the more concentrated hot gas impingement onto the shielding material. If the shielding material were highly conductive -- e.g., thick copper instead of thin stainless steel with an air gap behind it -- the thermal conductivity (heat spreading) could in principle be sufficiently high that, assuming a large enough surface with only some of it heated, it could conduct and then reradiate or convect back into the air the heat input such that all parts of the slab remained below the critical temperature. A heat pipe like architecture could also be imagined performing this function with less copper employed. The GE backspash, however, is the more practical approach.

Get a 1/4" x 1" solid color solid surface molding fabricated and installed please. That's way too much gap for caulk.

Where there is a will, there is a way. Premium Grade 1 x 6 ripped to 5 1/8" backed by cuts of a 2 x 6 ripped the same at custom lengths for each to make up for differences in depth to the wall. Screw & construction adhesive 2x6's to studs, 1x6 to 2x6 pieces, then backsplash to 2x6 . Add 3 1/2" casing painted with semi gloss that matches trim, and done!