Paragon sliding dropouts are a builders favorite
Adjustable Dropouts - all - www.paragonmachineworks.com
the disc caliper mount moves with the disc on the Hub.. the '
Soma Wolverine' appears to have a knock off of those..
perhaps A licensed Copy since Merry Sales Importer [aka Soma] and Paragon are across the SF Bay From Each other.
Eccentric BB also Tensions The Chain , while the Hub disc and Caliper remain in 1 place.
then a Top of the Chainstay Caliper mount Location , solves pannier-rack interference ..
How do you run a rack with seatstay mounted disc calipers?
racks that use the skewer can use a 5mm bolt and spacers instead of the Skewer
Higher grade Steel Bolts (8mm hex head marked 8.8 ) were what I Used at the bottom of my Racks ..
they get a dab of paint on them since that is not a Stainless type alloy..