I'm not sure how they don't address your needs. You want to support 2 aspect ratios, 3:2 and 16:9. The height or width don't matter as such, it's just the aspect ratio.
What I've done on 2 projects is:
set Scale outer on my project
set Window size to the 16:9 aspect ratio
make the layouts' width to the 'wider' aspect ratio (e.g. 3:2)
make sure the important stuff is in the 'safe zone' of 16:9
I did use Anchor on one of those projects to keep buttons on a button bar in position.
So anyway what happens when you try to use Anchor, even in a test project? Can you provide a capx?
note: I have no iPhone app experience, but as far as I can see the above holds true.