Register New Site - Page Template

Hi there,

I'm wondering if there is a way to create a template page for "creating a new site" form.
At the moment when logged in users want to register a new site they get a layout that is not looking nice at all. I've tried to contact the designer of the current theme I'm using but it seems there wont' be a solution or update for it anytime soon.

So I was wondering if there is a simple solution, like creating a page template (widescreen, no sidebar layout) that could be used for this that would also be easy to style/adjust or suit the theme (or any theme)?