Idea for background/cover

[BCOrchidGuy]

I've been thinking about an idea for a back ground for my new tank. I first thought of this a couple years ago and just kept it in the back of my mind but now that the tank is almost ready to be filled with water I'd like to get some feed back on my idea for a tank background.
I was thinking of either using silicone or epoxy and completely covering the back glass of the tank with very small reef rubble OR very course aragonite. I thought I could even put some larger pieces of rubble on there to make ledges etc...
What does everyone think, what would be your concerns?

Doug