I came up with a method of doing mental math to triangulate the stronghold pretty consistently. The only math you have to is addition/subtraction.

This video explains the math and shows how accurate it is:

I linked the second half of the video that details the mental math portion. The first half of the video talks about calculators and shows accurate they are (I completely agree with the ban). My method is a little less accurate but is overall still pretty good.

While I personally don't think that F3 should be in its own category, I simply want to provide some more data on whether or not it's worth considering.