vaderios, I wouldn't worry about any CGI being used here and there if necessary, as I'm sure it will only be included if it's as good as the stuff previously done for 'ANH:R'.
I really liked your speculation on how the background 'cloud' lighting might look in this shot eventually, now that we have a rough idea of how Luke's 'approach' shot is going to look.... With or without any buildings in the distance at this point, I like your effort.