while it certainly could be a failing stator, I would not jump to that very expensive fix first.
1, you could be right, the HID balast could be malfuncitioning and drawing too much current. Looking at your loads listed, it should be ok if there is no malfunction.
1a.....some other device could be drawing more current than normal...check those out too.
2, your battery could be dying...check that out.
3 your regulator could be male functioning too.
4....yep could be the failing stator