I have the replacement tank, and my spare. To put another tank replacing the spare tire would be nice for extended range, but at $1700 I can put in a far larger in bed tank, and other goodies VS relocate the spare into the bed and fab up some sort of mount.
2007 Chevrolet 3500 CC/LB Duramax/Dually 4X4 Mine r4tech, Reese Signature Series 18k +slider, duratrac, Titan 62 gallon, diamond eye, Cheetah 64
2011 Keystone Fusion 405 TrailAir & Triglide, Centerpoint, gen-turi, 3 PVX-840T, XANTREX FREEDOM SW3012, G614