Multisite Signup Page Template

Wp-signup.php uses my home page's template. This is not a good solution for me as I have a big banner on my home page that is distracting to have on a signup page. How can I disable the header on my signup page, or choose another page template for my signup page?

Here's my signup page: http://africaretails.com/wp-signup.php

Thanks in advance for any help with this! Its pretty urgent.