Please add the 5 GHz to your BeagleBone Green! Or launch the BeagleBone Orange with the 5 GHz only WLAN. Should be rather easy to do...
Without doing my homework I think that the 5 GHz WLAN could be done just by WLAN controller and crystal changes and even the board could be essentially the same.
I mean 2.4 GHz and 5 GHz WLAN or 5 GHz only WLAN.