From iPhone tableviews to universal app; what components to use

I've built an iPhone-only app for conferences. The datamodel is as follows:

There's many conferences
1 conference has many tracks
1 track has many presentations
1 presentation has many speakers (usually 1 and not more than two, but okay)

For the iPhone, this is ideal: just drill down from tableview to tableview, with some details above the tableview if necessary.

Now that I'm building for iPad, I thought I'd use multiple UISplitViewControllers:
- Conference list with conference details
- Track & presentation list with presentation details
- Speaker list with speaker details

This seemed very attractive to me, since I could use just one storyboard for all devices. But it seems that UISplitViewController needs to be the root view controller and without tricks, you can't use more than one.

Any idea which components to use? Preferably, I'd use a single storyboard.