I apologies if this has been covered already. Your supplies got a little lost in the "You shouldn't even consider it" sidebar. (I'm not a fan of the "it's impossible" arguement, BYW. You asked for ideas on how to make it work so let's focus on that, shall we? Every problem has a solution, so let's find them!)

I'm thinking about feminine hygene. If you're of the XX construction, you need to make this a priority. Be sure to include these needs in your preps.

*you and your daughter need to be able to clean yourselves daily.
*Water + soap + cloth and/or wipes should be on the list, and enough for a few months at least (your daughter is still young enough not to have to worry about Auntie Flow, but cleanliness is a life-long issue for us, UTI and yeast infections are quite frequent in girls)
*canestin and cranberry pills would be a valuable use of space in your pack for a trek of this length
*reusable pads are an option worth considering once you've got you water supply figured out.
*Tampons without applicators are probably the most pack-friendly
*pack extra underwear for accidents
*throw in some extra garbage bags for laundry and fem product disposal