I' ll support the Mcnaught pump as well, having and still using one our days as back up inside our aircraft luggage bay. They are very quick ( 1turn 1 litre) easy to use and maintain. The pump shaft used for 44 gallons will also seperate into 2 pieces, so the whole set up, ie pump, shaft, filter glass, handle etc, will fit in a medium size backpack, probably 2-3 kgs max weight.
Cheers
WLM