Not that I'm aware of. The concept of building or modifying your water is to simulate a known water source (or an imaginary one). If you were a brewer in a location with a given water supply, the brew would also concentrate the ions through evaporation. Note that your CL:SO4 ratio wouldn't change either. You'd simply end up with higher concentrations of each.
It's really hard to judged a beer's finished bitterness in prefermented wort.