My Rohn catalog dated 1987 states that anchor alignment has a tolerance of
plus or minus 0.1 degrees. If you have a 100' tower with an 80' guy radius
your anchor location would have a tolerance of plus or minus 1 11/16 inches.
You certainly could not site a tower leg this close by eye. In fact it
would be difficult even with a transit.
I have used various methods already mentioned and my towers are still
standing, although probably not in tolerance. For one house with an outside
fence I made an AutoCAD drawing and measured the anchor locations from the
walls. I have also installed stakes at some equidistant points and used
ropes along the ground to line up the anchor. I have also used a transit.
Even a transit is difficult you're installing anchors for an existing tower
because you can't set it up in the exact center.