I have asked three dealers and get the same answer... "I don't know"
There's not a shock in the world that is going to feel the same when you nearly double the load on it. You're either going to have to run it still when you are solo or allow it to be sloppy when you're 2-up.. . . I don't want to have to change it every time my wife rides with me. . .
Softail shocks work backwards Chas, because of the mounting. They are longer when loaded. I set mine for half the travel with me on it seems to work well.There's not a shock in the world that is going to feel the same when you nearly double the load on it. You're either going to have to run it still when you are solo or allow it to be sloppy when you're 2-up.
Or you hit the middle.
You don't need a setting, you just set the preload correctly.
Jack the bike up until the rear tire is off the ground and measure the total length of the shock from the two points at which they attach.
With the bike on the ground and you sitting on it, have someone measure it again. It should be as close as possible to 1/3 less in length.
^This^Softail shocks work backwards Chas, because of the mounting. They are longer when loaded. I set mine for half the travel with me on it seems to work well.