Thanks everyone!
I'm usually no good with the artistic part in games, and since Custom Objects offer very little in terms of technical features, I thought I'd make use of those few as well as I could. That is, basically using Layer 6-7 objects in the place of normal tiles so that you can finally 'hide' Juni behind them.
I think that with some effort one could make really cool-looking 3D perspective levels, or even fake some scrolling. But that's it, any other application I could think of is about the atmosphere.