The trick I have found..

Is to space the wires 12 inches apart, as close to the feed point as
possible.
With my antenna, it goes from the feed point to a 12 inch separation 18
inches from the feed point.
The wires are 12 inches apart from that point on and there is very little
interaction between the wires if any. At least my antenna analyzer cant find
any.

Like I said, the trick is to move the wires away from each other as close
to the feed point as possible.
I have found with this set up, that wind etc. changes very little.

Like I have stated before, my wires are hung under each other, so I have no
idea if the same concept would work with a true fan dipole....



I find that trying to prune/tune a multiwire antenna (like a fan) is an
exercise in frustration because of the strong interactions among the
elements, aggravated by the fact that most people install antennas in
places other than a vacuum. there's wind blowing (which changes the
spacing), trees, other stuff, etc.