Theoretically, you can get to 115 skill using NO leather, by making cloth ninja hoods.
Those hoods are donatable to the Thief at the Britain Library, if you choose that route.
As for leather use, I've got a sticky post asking people to PLEASE submit new gain logs for the crafting skills, to make use of the Samurai Empire and Mondain's Legacy items that are (in many cases) better choices than the AoS and earlier skill gain charts - but no one has submitted any except me (and I've only gotten around to doing 110-120 smith so far).