Axle location with torsion axle ?

[rustytoolss]

I've read about the 60/40 general rule for axle location, got that. But my pop up frame has a torsion axle. I want to add to the over all length. My question is....when measuring with a torsion axle. Do I measure from the center of the axle unit....Or from the center of the spindle/tire location. To figure out my 60/40 location. Hope I get my meaning through, where you guys know what I'm asking.

[MtnDon]

Spindle location