Thanks for the responses.
That's what I'm using in my field code, but the logo isn't always visible. Not sure why?
When I open the document, it looks like this:
If I open the footer or update the field, then it looks like this:
And the floating graphic is pretty much the only other option I had come up with, the anchor on the last page, but your comments are exactly why I don't want to use that option either.
I've attached the word file.