Since I don't have the fab skills of some of you, I had to resort to thinking my way through the fuel filler. I started with this,
IMG_0249 by
Robert Moorman, on Flickr
On the left is a filler connecting tube I found at NAPA, on the right is the S10 filler tube I got on Ebay.
I cut them into sections that went together like this,
IMG_0251 by
Robert Moorman, on Flickr
Added the filler cap on the outside, and it looks like this
IMG_0250 by
Robert Moorman, on Flickr
It's inconspicuous on the side of the bed and while I haven't tried to fill it, I think it will work just fine.