very quick tip re external structure and scenery\world\scenery

Noticed from Flytampa instructions and others about when creating an external folder structure if you want - people are concerned that scenery\world\scenery type .bgl's  ALT, traffic and so on, have to be in the root scenery\world\scenery or they won't work.

No they don't.  Just ensure your folder type is World (or Global if external Global)  - and the scenery library entry is at the bottom, right above Default scenery and Default Terrain  (scenery\BASE and scenery\World).  Your addon  ALT.bgl's  and traffic .bgl's will then work fine