Applications :: ITunes And Remote Music Library - Reselect File Location

I've got to a point where the HD on my MacBook is just too small to hold my music library, so for a while now, I've been housing it on an external drive hooked up to an Airport Express. My setup certainly isn't without its fair share of problems.
Setup: I keep my own folder structure, with folders for specific categories and playlists. iTunes's music folder structure has never been organized enough for me, so I don't use it. Another reason is I have music in my library that isn't in iTunes (since I don't frequently use it). My music library resides on an AirDisk, while my iTunes database along with some local music folders resides on my Mac.

Problems: Whenever I move songs/albums/playlists from the local storage on my Mac to my remote library, I have to go through and reselect the file location on the AirDisk for every file. I've also noticed that files on my AirDisk typically appear with an exclamation next to them, won't sync to my iPhone, and won't play in things like iTunes DJ unless I manually mount the AirDisk. Even then, iTunes only sees the specific song I clicked. iTunes still thinks other songs on the AirDisk are unavailable (even though the AirDisk is mounted), and thus skips them when playing unless I specifically click a song. Finally, whenever I move my music library around (like putting it on a NAS), I have to go through and manually change the location of each and every song!

All of these problems makes me think there has to be a better way! I've read about using iTunes to relocate the iTunes music library or database to a different disk, using the "Consolidate Library" feature and other built-in features, but it doesn't seem like any of these would work with a custom folder structure. I also know there are various 3rd-party "helper" apps available, but I haven't looked into them. Perhaps a 3rd-party app could simplify the process?