Most of the French uniforms are grey, with cuffs in branch colors. I bet Confederate shell jackets, perhaps for bugler, could be bought off the rack and require very little alteration. Add pants and a plain overskirt. Maybe find some of those long bureau cloths that used to go on top of diningroom sideboards, they often are white with lace border trim, and use as the long apron covering the front of the skirt. A couple of the sutlers sell wooden barrel canteens that could be painted and decorated. I know a few also sell more substantial wooden kegs for water. Maybe the smaller gallon or half-gallon size and add a cartridgebox strap.