Q: Viewport question

I have an Apple fixed layout template, I need to know the following:

when looking at a book done from this template I see a two page spread with some grey background in landscape on my IPad2

if I turn to portrait I still see the two page spread with of course the larger grey background top and bottom.

Is there a way to have the book view as a one page spread in portrait where it fills up the entire screen?

viewport is set to 560 x 720

here is the display options.xml file

<?xml version="1.0" encoding="UTF-8"?>

<display_options>

    <platform name="*">

        <option name="fixed-layout">true</option>

    </platform>

    <platform name="iphone">

        <option name="orientation-lock">portrait-only</option>

        </platform>

</display_options>

thx

R