I also think it's to late to change the scenery now.
I have done some test for adding one or 2 Column of Terragen tiles to the east, that is possible , but you must understand that this is not like just adding a new part to a picture
it's a new scenery with more columm than the old one and the terrain must match 100% the old one. I could add 3 terragen columm (3x23.040 km)east , but that means that I have to rename all the .dds textures since the t0000.dds is all time the lowest right . Importing all the airports or TP is also OK , BUT
all the Big work about altitude corrections around airfields and the huge work for positioning with precision my objects is lost .
Putting the windmills and Pylonnes like this on the texture is very time consuming !!
and this is just an example ... it's the same for all objects that are not inside an airportO.cx
I can't do this again for just some km more..