One option, which may mean waiting, is Cinemax in US. Very often, Cinemax starts broadcasting the films one they are finished being broadcast on HBO. In the case of X-Men: Days of Future Past, Cinemax showed the Rogue Cut, while HBO showed the theatrical. Perhaps this may happen again with BvS. It will take some time to see.
But the problem is that there (not that I’m aware of anyway) wasn’t a 16:9 master done for the extended cut, only for the theatrical.