Well as much as my heart goes pitter-patter for Christina Hendricks, I'm not sure she resembles Anna Nicole enough to help with suspending disbelief.
At least this Agnes Bruckner resembles her a bit.
Since prosthetic boobs were used in the movie, it made me think they could have used another actress who looks like Anna Nicole a lot in the face.
Alexis Texas, though she is a porn star, looks and talks just like Anna Nicole. She also grew up in the same part of the state as Anna Nicole too (Alexis in Castroville, TX, Anna Nicole in Mexia, TX). YES of course I realize Alexis Texas does not have big boobs. But if prosthetics and padding are part of the protocol, then she would have become my first choice: