Understood, but really the main difference between ORBX quality and non is mostly texturing of models and the lots of little things like the flows and 3D grass. I always take into account the area around the airfield also since you will be going over it time and time again.
What do you plan to have based there virtually? I know the british had Gladiators and Hurricanes based there in 1940, but after that it was a big hub for the germans
Do you use SBuilderX? If not, I can try and rearrange some landclass to give you a better background for your AFCAD since the area as it stands in FSX is rather busy and modern.