Any suggested home methods / links of measuring sit bones to determine a size starting point for saddles?

And yes, this is a softball for a few here...

If you can find a sandpit, level off a damp but not wet section (so the sand stays together rather than runs).

Sit down on it, as though you are squatting.

Measure between the centre of the two indentations left in the sand.

Corrugated cardboard works too... in case you don't have any sand.

Someone needs to design an apparatus that allows a rider to customize a seat. Frame builders beware, you forgot an important element.

A damp bathing suit. Sit in some dry newspaper

carbon paper, and a sheet of paper sandwiched on either side.

Not user customizedThere is a Manufacturer of a custom carbon Fiber shell for your High End Race Bike..

and a wing adjustable saddle, see in UK based St John's St Cycle..

I put flour in a large ziploc bag, lay it out flat on a chair and sit on it (gently, of course). I read about this method somewhere on the net (probably here). It was also recommended to use a foot stool to raise your feet/knees a bit for more accuracy. Used the measurement to help determine what size of Specialized saddle to buy. It's basically a home made
ass-o-meter.

I just used a Bontrager system today and understanding how it works now, a memory foam cushion would work well. Specialized even recommends using a foam pad as a home method, sit then measure between low points on each side.

Paint roller and a sheet of clean paper. You can figure out the rest .

Why not just duck into your LBS and "borrow" their width meter? It's usually just laying around anyway.

Bread = food grade memory foam.

Seriously, I've done it - two slices of bread sitting on the coffee table. Measure the width between the depressions.

Don't eat the bread.