A way to force a campaign to be able to test how it looks on the website

[mitar]

I had some issues with a banner-based campaigns in the past that they destroyed the layout of the website. I have just been updating the theme on my blog, but I am unable to test if the banner campaign will block it again. Is there a way to force rendering of some past campaign just to see how it would look like? Do you know which one had a banner which pushed the whole content of the website down?