On the face where the toe kick would be, you can by a thin veneer to glue and staple over it. That would leave you the edges you still have to sand.
Depending on the water staining you may not be able to get all the staining out. I have never stained ash, always painted. Not sure how it takes stain, if you go with a darker stain it may hide the water staining better if it doesn't sand out.