gas tank question?

[MountainMan83]

Ok I know it's been awhile since I've on here, but I have a question about relocating my gas tank. I would like to sometime in the future I would like to move my gas tank location to the spare tire mount area using either a 22 gal E-series tank or a 19 gal F-series rear tank, thought about a 23 B2 tank but it didn't sit right with me. Anyways, I show my idea to my bro and he was alittle concerned about the gas tank possibly being outside of the frame. Right now my Ex is my daily driver and will be for awhile, so he was concerned about rearend situations.

Any thoughts about the safety issues of this setup?

 

[Jason94sport]

My 1st question would be why? What purpose does moving it serve? What will you be doing that would require to move it?