Ben,
In a disco you can't add more than 50 - 55 L even if you use the space behind both rear wings, even less using the space between the chassis and the sills. Unless you make the tanks yourself, the job is pretty costly (in the UK). To make a real difference, an extra tank should hold well over 100 L, otherwise it's cheaper and easier to carry to use five jerry cans.
For reasons of practicality / convenience / economy / cost - an internal tank is the best solution. Have you considered a flat tank under a false floor?
------------------
Roman (UK)
www.polandrover.com
__________________
----------------
Roman (UK)
|