Top header banner design width

[mrmontez2000]

I will be designing for this site, though i am new to vbulletin so have a question
http://www.militaryjeepers.com/community/index.php

I need to design them a header banner that is going to be an image that spans the width, right now i see its setup with a logo and then repeating background images to allow it to stretch and conform to peoples resolutions...but in turn that limits my design to having to use that forum of repeating simple background in the bar...
my question is how can i bypass that to design a solid banner across the top that doesnt need to shrink, therefor allowing me to be free with the design in a wider sense...
or is there a way to make the design portion space on the left wider so that theres a very small amount of repeating-stretch area?

thanks all!