A very interesting question! The different cultures also have to be taken into consideration, Life on the "frontier" was a myriad of peoples all with their own leather working processes, Indian, French, English, etc all had different techniques for working leather. As well stature played a part rich folks got imported leather goods poor folk made their own. I always use a character model when doing era related projects, was my guy a poor French trader, if so he may have some American Indian clothing as well as French, or an English aristocrat coming to find adventure who may have all new English made attire. As for finding the answer to burnishing I think you have to narrow down what cultures leather processes you intend to copy and look at museum pieces for your answers. BUT if the info is so hard to find then who will know if your wrong and burnishing is basically doing what time does to leather , wears the edges and makes it rounder and smoother.