My view is that this is a fairly futile debate. In the event of losing both pumps in that tank, you have no choice but to use the wing tank fuel and accept whatever trim change occurs. The change in trim between the time of pump failure and landing isn't going to be any worse than that when you do a sector with wing tanks only, because that CoG change is all that is occurring.
SO, as stated before, range and endurance will be the relevant considerations, not that your useable fuel has been drastically cut. You'd want to land asap, even overweight, as the wing fuel has a bending moment that counteracts the mass in the fuselage, as you are now likely to be above the MZFW on landing, and of course that means choosing a field with the required performance attributes and landing as gently as possible.
As for the green band, I think that is indeed for take off only and in a non-normal, standard limitations no longer apply; what is you alternative to flying outside the standard trim limit in this event?