I doubt there is an "easy solution". You might need to place multiple Flying Blocker all around your cliffs. Note that it does not work like ground pathing and therefore the air units will just bump into air blocker if they are told to move through, which can be annoying. You might want to play around the unit collision and set different flag / setting or whatnot...
About the vision, there is a new tool that I did not explore much that you might be able to play around with.
Under "View -> Show Vision" you will be able to see like the in-game fog vision but in the editor. So if you place air units and see what block vision that would help. But I don't know what block air vision... Maybe if you "air unit" has some kind of ground flag with it... but then it wont move up/down cliffs... but if you add the collossus it would be then it wont move across very low ground or ramp sides...
I doubt there is an "easy solution". You might need to place multiple Flying Blocker all around your cliffs. Note that it does not work like ground pathing and therefore the air units will just bump into air blocker if they are told to move through, which can be annoying. You might want to play around the unit collision and set different flag / setting or whatnot...
About the vision, there is a new tool that I did not explore much that you might be able to play around with.
Under "View -> Show Vision" you will be able to see like the in-game fog vision but in the editor. So if you place air units and see what block vision that would help. But I don't know what block air vision... Maybe if you "air unit" has some kind of ground flag with it... but then it wont move up/down cliffs... but if you add the collossus it would be then it wont move across very low ground or ramp sides...
Good luck.. xD
Working on projects: