I don't get the bickering over extra weight and all. The extra weight is negligible compared to the additional range. I know I for one would certainly spend a few hundred towards replacing a fuel tank for higher capacity if it was easily done. That said, this all is just a bunch of wishful thinking anyways, wasted effort.
For differences like this, there is usually reason behind it as it cuts into the whole economies of scale thing with the parts. It's not like someone was like hey, lets screw one market with a smaller tank for the hell of it while everyone else gets more. Even if everything matched up and fit perfectly and wasn't due to some slight configuration/equipment differences in the area, it could of been something as simple as an insignificant 20-30lbs difference on a single car that may mean .001 MPG or emission...that IS significant to the manufacturer when multiplied across hundreds of thousands of cars produced as far as fleet averages, epa regs, etc go.
What makes it wishful thinking and wasted effort is assuming everything is perfectly interchangeable, what difference does it make when you cant get the parts to do it! It's not like you are going to go to your neighborhood ford dealer and tell them to order you the 62L tank and go pick it up in a week. Unless somebody is selling these things, it's all pretty moot. Even trying to source one elsewhere...pretty much anything can be imported, at a cost....but where are you going to draw the line? Just the existing fuel tank is a $700+ part through the dealer (look it up!), and you may need sender/pump if it isn't the same which could be significant, and other minor parts like straps and all if they aren't the same. Assuming prices overseas are similar, if/when you found someone willing to ship to the US, your going to be in for a lot higher then that even. Somehow I don't think many people will go through that hassle and the great expense to try that way either for simply a few extra gallon capacity.