i'm not so sure you would even need to those bottom mirror pieces... i popped off my mirror cover yesterday so i could get a look down there & here is what i saw...
Here is the mirror part off ECS
I don't know what those extra pieces on the side are but the camera points down & i already have holes for those screws. i'm gonna pick up 4 of those screws to make sure what i have is grooved for screws. I can just use a step bit to drill out for the camera... I know the part is only $15 x 2 but i'm not sure we needed it.