Saving a game specific configuration file through the Quick Menu in Retroarch will have the bezel load with the game. Although you do have to set it up first. And I’ll be damned if I’ve ever been able to quickly have a game screen fit automatically using the pre-set aspect ratios… I always have to shrink or grow the screen and move it around to get it to fit. Once you have it done, though, as I said you can save game specific configs that launch with the game.
And I’ll be damned too if I know how to assemble a game bezel. Although your render of the pieces looks great, Lumber.