Praise be to Allah.
What I think you should do is to do that which is mentioned in the hadeeth of Umm ‘Atiyyah, so wash the deceased with water and lotus leaves each time you wash him, starting on the right and washing the parts of the body washed in wudoo’, taking care to remove any dirt etc, each time you wash him, until he is clean, even if that means washing him more than seven times, because of the hadeeth mentioned. There is no need for soap, shampoo or anything else, unless the lotus leaves are not enough to remove the dirt, in which case it is o.k. to use soap, shampoo, potash and other kinds of dirt-removers from the first wash, and to put some camphor in the final washing, because of the hadeeth mentioned. This is the Sunnah as far as I know from the saheeh ahaadeeth, because of the hadeeth of Umm ‘Atiyyah and similar ahaadeeth.