Since you state:
All of my (text) files are currently
stored in UTF-8 with the BOM
then use the ‘utf-8-sig’ codec to decode them:
>>> s = u'Hello, world!'.encode('utf-8-sig')
>>> s
'\xef\xbb\xbfHello, world!'
>>> s.decode('utf-8-sig')
u'Hello, world!'
It automatically removes the expected BOM, and works correctly if the BOM is not present as well.