Brilliant tests ! Thank you very much, it is very useful. I've read it and it's top notch.
Most helpful. Glad I finally have something to show to people who didn't believe me when I said I didn't see how a tapered piston would change anything.

One thing I'd like to remark as I couldn't find anything on it is the tolerance of the piston/cylinder itself.
On my shocks the cylinder bore is 12.04mm and the piston itself 11,87mm.
That's a 0.075mm gap all around which is not bad but will influence of "hole" area.
So cylinder bore area = 6.02²x3.14= 113,795mm²
Piston surface area = 5.935²x3.14= 110.604mm²
Gap around the piston = 113.795-110.604= 3.191mm²
Which is not negligible I think.
Plus the inner piston hole on the rod which will also "leak" a little but this is possibly negligible.

Again many thanks for such precious info ! Looking forward to more tests .

Jonathan