on the shallow end of this, rather than putting in a beveled piece of wood (the piece you screw the slats too) can you just bevel the slat itself and screw it to the MDF (back wall)?
Sure. Or, if you're not worried about it because no one will see it back there anyway, you can just leave it rough-cut and be a little more cautious when screwing it to the 1x2 behind it. You could probably use a 2x2 without changing the performance too greatly.