I usually like to play zoomed out as far as I can while seeing the symbols for outposts, watchtowers, ect. However, I find it very hard to get that exact zoom out where I know I'm zoomed out as far as I can be, before I lose the symbol details.

Is there some shortcut key, or some easy trick, that I can use to help me switch to that perfect zoom?

I dont think there is... I'm sure someones developed a trick for their own computer to do something like that tho...