Well, no, I'm not saying that just plain water soaking would help. Why do you think cowashing daily would be bad on your hair exactly? If you have dry coarse hair, it needs more moisture. To do that, you're going to need to condition it a lot more often than its currently getting. I have low porosity hair that is resistant to deep conditioning too, but I've found that the daily lighter conditioning helps it, as does steam deep conditioning. I don't have a steamer, but I wrap a hot, wet towel around it for about thirty minutes.
Basically the bottom line is with your hair being dry and unmanageable, it needs more moisture and it just sounds like your current routine isn't giving it quite the moisture it needs. Hair loses moisture, so a daily cowash (which is just a daily condition basically) would help dramatically.
Curly work in progress
2C with some 3A if all the stars align
Low porosity, medium to low density and fine
No sulfates since 2009
CG since 2013
In my stash:
Shampoos and conditioners- Tresemme Naturals Low Poo, Tresemme Naturals Moisturizing Aloe, Suave Naturals Coconut
Leave Ins- Kinky Curly Knot Today
Stylers- KCCC, AG Recoil, KY Lubricant (yup), SM Curl Milk
Gels- Ecostyler, Biosilk RHG
Mousse- Devacurl Uplifting Foam, Suave Captivating Curls