Longer range fuel tank(s)

[Talonmotorsport]

While siting on the thinking chair waiting for the penny to drop I was thumbing through mini mag and came across replacement fuel tanks. In the 'real' mini as in Austin the tank sits in the boot in the corner and still leaves room for a pair of spare pants and a tooth brush much like the Roadster. This got me thinking what if you had another two fuel tanks that sat either side of the main tank still leaving a small boot space? They would sit between D13 and the curve of the rear tub. If they where plumbed in low with shut off valves between the tanks, you could run round using just the main tank and when you go touring open up the valves and have another 16+ ltrs to play with. You would need vent pipes between the two outers and the main other wise it will not balance, and when the fuel is low again shut the valves.
Can any body see any potential problems with this idea besides added weight?