What a challenge! hehehe You CAN do it. (just not sure how lol)
Go the flats

And just take a bucket or buy one from the local hardward store (about $13). Put the nappies in there and when you need to wash, add water and detergent and use a broom handle to agitate.
Good luck.
Cas
P.S. Take a look at Kristy's thread when she went away without nappies! Might give you some ideas