Moving the Gas Tank from behind the seat?

[JRBECK64]

Here's a couple of questions for anyone who has put the gas tank between the frame rails. Is there a tank that would fit between the frame rails and would be able to accept fuel from behind the Licence plate like on a lot of the older cars? The second is has anyone found a spacesaver spare tire that fits the original 6 lugs on these old trucks? Im asking the question about the spare because I want to put the spare behind the seat where the tanks used to fit and I know a full size tire wouldn't fit. Thanks for any help you could give with this.

JRBECK64