Creat a strict with a panel as a member. Include stuff in the strict to tell things such as passable objects like clouds and background objects and how it can collide. Such as hitting a wall to the die but come from the top you can fall through it. Now set uP an array and have every object on the screen in that array. Now when you move your panel with your collisN detection functioniN check that panel with every Panel in the level to see if any of it's x or y positiOn plusThe size of the panel. This may seem Complicated and it is. But start small and build up. Also the 2.5d option is much easier.

Ps. Typing with an iPhone is annoying.