I have added, modified, or removed vegetation on the approach path and around the field.
I have covered clouds or other imperfections in the aerial with aprons and/or vegetation.
I have added aprons to roads in the vicinity of the field when they appeared to be helpful for orientation.
Never got a single complaint, let alone the dreaded DECLINED.
If you want to try the limits (both of the technology and of the mod’s tolerance), you could use KHOL to remove all the spurious white buildings covering the dunes in White Sands, New Mexico.
I flew there the other day and was quite disappointed that this wonder of nature (and historical landmark) was littered with mis-detected warehouses (or whatever the default non-residential buildings are supposed to be).
I would be tempted to actually do something like that IF I thought that the team was using World Hub input to train the AI system to better generate buildings in the future. I asked that question in a previous dev stream and it was not answered, so I am going to assume that no, it does not.