I bought a similar aluminum tank from Summit Racing thinking that if it was sold for racing that it would be excellent equipment. Mounted it like a top box with gravity feed. What could go wrong? Took it to Deadhorse and Eagle Plains and a lot of Far North gravel road. Basically, the mounting tabs fractured. There was a thin sheet of roofing rubber between the whole of it and the mounting plate. The idea was to eliminate/dampen any vibration or scuffing between the two pieces. This worked great for a road bike. But failed on the Haul Road. IF...I was to do such a thing again, I would make a set of cross-straps to fit over the the tank to keep it in place (fore-aft-vertical) when the tabs fractured. Maybe lined with some hard rubber for some tension.
The alternative is some sort of poly tank properly bracketed which I suspect might actually work much better than aluminum for our purposes.
I would schedule a regular and careful inspection of these mounting tabs at least daily if not at every fuel stop while the tank has fuel. I was very surprised to find 2 broken and the other 2 well on their way to separation one morning in the Far North.
ALSO...I would mount the tank in such away that in a crash it would not drag directly on the gravel/pavement. The aluminum is very soft and abrades thru in less than 20 feet of its own weight plus fuel. (Makes me wonder how such a thing ever got past any kind of race tech inspection/testing?)
As a personal preference, I hate giving up the pillion place to mount aux fuel. But that area does seem to be a location that minimizes mounting problems.
And as an extra special hint for those running aluminum tanks having any kind of cap that can't be replaced at the nearest auto parts store or big box store, tether the cap real well. If it is a weird cap, carrying a spare could be a good idea even if the original is tethered. If it is an ordinary cap and one is on a big (rally? Cert?) ride, carrying a spare is still a good idea with the original tethered. Ask at any fuel stop if they have collected any lost fuel caps? There is usually a box of 6-8 that they give to customers who have found theirs missing and hoping one of them might fit.
fran