I never had issues with my application. But maybe that is because of my work background- so I'll share with you how I get accepted the first time with just one website.
I've been designing for print/web/video since 2002 and I have portfolio site that contains my mixed projects. I submitted that portfolio site to ePN and explained that I am in the process of building a high traffic network and that I intend to monetize it using ePN. I also explained that I can probably promote ePN to my existing client sites.
I don't have any affiliate sites when I applied and all I gave them is a promise that I will promote ePN and I got approved right away. So my suggestion for those who want to get in-- create a portfolio site with a proper contact us page. What's a "proper" contact us page? It's the one that has your name and contact info and not just an anonymous contact form. Include your drawings, sites you designed, drafts, etc on the portfolio section. Do not make your portfolio site look like a landing page. Hopefully, ePN will see your potential and approve you right away.