I do have to say that in that patch above, as a rule that is a no-no as the seam will end up showing in the form of a "ghost line" when the bonding shrinks and expands at a different rate.
That being said, we just did a 2017 BMW M2 where we put a quarter on, following the BMW guidelines bonded the seams with a backing just like you will see in this video. We used the BMW metal filled "bondo" to finish it off just as they did in this video.
There are other metal fillers like Evercoats "Metal-2- Metal"
http://www.evercoat.com/product-deta...ber/100889/us/
So you don't have to use the BMW product but that it is a guaranteed system.
Check it out, pretty wild! I would have wanted to slap someone suggesting this back just a few years ago. But there it is, one of the biggest automakers in the world known for some pretty high quality, glue that baby on! LOL
https://www.youtube.com/watch?v=YGC3dFCRgGM
Brian