What's this for specifically? If its to switch for different resolutions, I suggest just waiting a short while for 1.8, it does it automatically with no issues - it switches tk2dSpriteCollectionData objects instead of the contents, and as such simply sidesteps all the rest of the issues you're speaking off. When assigning to a sprite, at sprite collection switch, the correct object is loaded in and cached.
If you want to implement something like that - I suggest doing something similar. There are a lot of references in there, eg. materials, textures, etc.
If not, let me know and I'll tell you how to strip out all the texture refs.