Race Face Sumo, & the Thomson, &

a USE (UK) spring/elastomer suspension* seat post are Zero setback.

* [It's a rider weight adjustable, good one]


FWIW, with a leather saddle like that or Brooks the Traditional 2-Bolt Campag posts were Fine..

the <C> dog leg wrench had a 10mm hex on one end, for those Bolts,
and an open end that fit the Brooks tension Nut, on the other.. for a Reason.