In the optical wavelengths offline interferometry is currently not possible afaik.. so you have would to directly combine the signals, which I deem implausible

In the optical wavelengths offline interferometry is currently not possible afaik.. so you have would to directly combine the signals, which I deem implausible to do in an non-lab setup, as you have to align the paths (from the individual telescopes to the interferometer) to a fraction of the wavelength.