Camp Washing Machine

One 5 gallon bucket with lid (preferably new), put hole in center of lid about 1-inch diameter

One toilet plunger (most preferably new)

Add clothes to bucket

Add warm water to bucket

Add soap to bucket (no more than 1/4 cup maybe less)

I would recommend that you bring Woolite-- a bottle takes up little space in your gear box, you need very little for a 5-gallon load, and you can use it in cold water so you don't need to depend on the availability of warm water.  Also, boys will tend to jam that bucket full of clothes-- make sure there's some room for them to move around in the water! Woolite also rinses well,
with fewer rinse cycles.