Is there any way I can customize the generated EPUB/text/cover.xhtml file created by pandoc?

Basically I would need to replace the default:

<div id="cover-image">
<img src="../media/cover.png" alt="cover image" />
</div>

By something like this:

<div id="cover-image">
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" width="100%" height="100%" viewBox="0 0 900 1200" preserveAspectRatio="none">
<image width="900" height="1200" xlink:href="../media/cover.png"/>
</svg>
</div>

The idea is to wrap the cover image in an <svg> </svg> tag so that it scales to the dimensions of the e-reader.

Note that 900x1200 just happens to be the dimensions of the default covers I generate on my system.

I am having a problem where my covers are not correctly displayed on the e-reader I use (ancient Kobo glo' with 758x1024 screen).

Thanks,