Ho Hum, this took off pretty quick,
Beachlover - there was a slight change of tack there, from desert island to fitting it into a rucksack and carrying the weight. The big thing about a lump of cast iron, irrespective of its versatility is that its a big lump of cast iron - it'll be very heavy, will dig into your back, will wear hole in your rucksack and be very heavy.
That said, I hadn't contemplated an aluminium one.
Gill, have you "seasoned" yours? It almost sounds as though it is rusting during the cooking cycle, mine came with a recommendation to clean it thouroughly then warm it up and coat the inside with oil/suet/lard etc and bake it in the oven for a few hours. The surface is said to absorb the oil and seal it against corrosion. Thereafter, never wash it with detergent, just wipe it clean with a cloth or paper towel, or use hot water and salt for really stubborn stains. As to where I got it, you'll all call me crazy, but I saw it while on holiday in Australia, bought it there and brought it home in the luggage price was about £12
probably about 5 litres capacity.
ATB
Ogri the trog