Happy to hear I at least gave you so,e helpful advice.
You seem to really now quite anit of stuff already which is why I decided to sign up and respond because discussing things of such a technical nature to a newcome to IOS or Apple products is a very lengthy process and in the end nothing is resolved. In your situation though I think we can exchange information with each other and I honestly hope you are correct with the symbolic link functionality and you will inform me of the results you achieve and how you achieved them.
With that said however the way an original ATV operated and could access info, while similar in some ways, is different in many others.
I think,it comes down to the original ATV allowing the connection of a USB device and ALSO allowed UMS abilities to mount and read the device. (UMS = universal mass storage, you may of course know this but for the sake of clarity included it).
The iPad however does not offer UMS functionality without the aid of apps available to the jail broken community via Cydia.
This is where the USB mount toggle for SBS settings comes in to play. This push button on screen icon allows the iPad to mount the drive or unmount the drive Sorry about putting a "Z" in my previous post, but as I said I was watching a ball game. I'm sure you understand.
Basically this toggle installed on the iPad needs to be push on to mount or off to unmount not having this the iPad will not see the connected device at all, presumably due to the lack of the implementation of UMS which is further due to them wanting you to use their iTunes match cloud service. All about money right?
So in the iFile cydia app when the device is mounted it recognizes it and can access any and all of the files. The iFile app also includes the ability to open any file and immediately play it without another application, as long as the media is iPad friendly, MP3 works flac files do not because iPad does not natively support flac much like flash video. In these cases when you click on a flac file within iFile it gives you options to "open it in another app" you have installed. such as apps readily available from the Apple store Buzz player, Av player, and literally hundreds of other which support audio or video and sometimes both.
If your collection is mainly iPad friendly music files the built in iFile player will play the file, allow you to skip to next file, fast forward, (using the blue slider bar) etc. when you need to access a different folder you simply hit back and open a different directory.
Ideally you can on your drive create playlist, genre, artis, etc folders which allow for easy access in iFile it is very user friendly and while playing music in a directory you can even hit a button which changes the screen to a list of all files in that directory and then you can simply click on the next song you want to play, similar to the native music app.
I found a write up which further explains this and I believe gives links to the software needed as well at the bottom of the post.
Basically you would still you a single app for playback but instead of the native app you would just use iFile.
One final thing is iFile let's you create "bookmarks" for directories. This is on the left side of the app which lists all available directories on the iPad. So i simply hooked up everything and created a bookmark for music, genres. Artists, etc then with just a single click I can access these directories instead of navigating the file system when my drive is connected.
Once the drive is mounted it stays mounted and when you want to disconnect it from your iPad you just click on unmount then disconnect the drive.
I agree with the bulky inverter option and rarely use it because I also have a battery backup on my iPad and unless I am driving for over 10 hrs (pretty rare) I don't need it, never really trusted them, they are bulky for sure, and some are quite noisy and annoying. I am always looking for a cleaner, better/more efficient way of achieving this so please let me know of you results.
Oh and since I have an iPhone as well there are now ways to remotely control an iPad with you iPhone thus has allowed me to keep all the stuff (iPad, USB hub, wires, drive etc in the glove box and using my iPhone as a handheld remote to control the iPad. Apps like AIrServer in cydia allow this functionality and when you get a call the music stops and you can choose to answer or ignore. I love this because I have missed too many phone calls from the wife because when I play my music I play it LOUD.
