3 separate BG images that extend beyond wrapper

I’m trying to customize the theme but before I attempt this, I want to make sure this is possible.
(I know anything is possible, but I mean for someone with decent web skills, but new to Joomla.)
I want to have 3 separate background images – one for the header, one for the body (which repeats) and one for the footer.

That’s not difficult in itself – Where I’m running into an issue is I need all 3 backgrounds to extend left and right beyond the content wrapper.

Image 1 is for the header, which would extend about 50px both left and right beyond the wrapper.
Image 2 is for the body, around 150px or so high, which would repeat all the way down the body and also extend 50px left and right.
Image 3 is for the footer, would also extend left and right, but like the header, would not repeat.

When it’s all put together, hopefully the whole thing will look like a scroll.

I don’t have a URL for you as I’m working locally right now, but I have a sketch. It’s too tall for a jpg attachment here, so I made a PDF and zipped it. (I know – I hate zipped files, too – I would prefer a simple jpg to post, but there is understandably an image height limitation here and the sketch is on 8.5×11 paper)

I’m using J1.57 and the Sandine II light theme.

I don’t necessarily expect someone to come up with the solution for me (unless it’s quick and easy for you.) I just want to make sure this is possible without major surgery. And maybe a push in the right direction.

I suppose another option is to widen the wrapper, and increase the far padding for every module, but I don’t know what is involved in doing such a thing or how that would ultimately look.