Re: background image 100% width 100% height
I would take the approach of using a tall thin gradient that repeats horizontally, with the background color being set the same as the bottom of the gradient. For pages that are tall, they just have extra of the background color at the bottom.
Or possibly adding a bottom Layer with the bottom gradient as a background to the layer, that floats with your bottom content?
That's what comes to mind right now.
Major Warden: Yes, there's always the unexpected, isn't there?
The Bridge on the River Kwai (1957)