Technique for determining heading offset

I’m running dual antennae and still tinkering with the setup.

When entering in the dual antenna settings I initially ignored the heading offset and left it at zero, figuring I had plenty to work on before fussing over that detail. I worked pretty hard to build an accurate frame for the antenna.

Now I’m ready to circle back to it. I tested some positive and negative values to see what happened and I noticed that being -0.5 smoothed out my heading chart a bit.

Anyone have any magic tricks for setting this value nicely?

I don’t have a fancy way other then trial & error but I did notice that the heading offset manifests a lot like a WAS offset.