At the moment I just have 2 plastic cans, they aren't proper fuel cans (not sure what their original use was they came with the boat, think they were probably for chemicals or something) carry about 30L each. I have one of the shake-syphons (a "Superpump" I got from Mailspeed Marine which I would recommend to anybody - completely spill free!)
John, interesting idea on using a 25L fuel tank, will look into that as my 6hp Suzuki aux, when it arrives, is supposed to have a fuel inlet on the front for an external tank, could kill 2 birds with one stone there.
On the subject of where, what's the verdict on weight distribution, better to have it up in the bow (where it is at the moment - strapped against the front of the console) or down in the stern? Running solo most of the time. so having ~ 60kg of fuel is the same as a smallish person.
The main thing is that the front of the console isn't vertical so if you tighten the ratchet strap the containers don't sit flat on the deck. Bit wary of boring holes in the hull but it might come to that; at the moment I don't have any fittings to screw to the deck anyway but a blitz on the "stainless steel bits and bobs section" in a good chandlery, is on the cards for when I visit UK in July
I don't use the cans much anyway at the moment as I am taking it out of the water between using it, with it being winter time, so I just take the whole thing to the petrol station instead. Get some odd looks when you turn up and take up half the forecourt with the Land Rover and about 8 metres of trailer and RIB on the back