I also dared using a selection list using the UITableViewController class on top of openGL view. I used a modified version of the generic class by Jeff Lamarche. This video tutorial helped as well to get an idea of how the code is organised for UITableViews.
So now I got a pretty decent on-the-fly level editor for the game. I can also select powerups for enemy groups and draw the enemies paths, etc. Still needs polishing, but it's coming together. This week I will try do a decent level, but for now with just one enemy type, and no boss.