WOOT!!! I have more research and an accurate time line thanks to Baron Jehan of Carolingia, Violet, and Lissa.
I now have the Renaissance Drill Book by Jacob de Gheyn. It was first published in 1607, which is “technically” just outside of the SCA 16th century cut off. However, the illustrations were done several years earlier in 1597, and publishing was delayed to prevent the techniques from falling into enemy hands. The book was originally titled Wapenhandelinghe van Roers Musquetten ende Spiessen. It is a military manual illustrating drills for Caliver, muskets, and pike. I just need to shift the project timeline from 1580 to 1597. But the reasons for the change in military uniforms are still correct. I just have MORE evidence to back up my original hypothesis.
Violet provided another reference book that has a bunch of wood cuts that I am still sifting through (I will remember the title later).
Lissa has been instrumental in finding an ancient map of “Germany” and many pictures showing striped fabrics in use in the region.
I have to say, the research and learning part is turning out to be a little more fun than the actual garb construction. Currently I’m doing the pain staking task of creating linen bias tape for all of the trim. I am hoping to have that complete tonight to take to Birka for sewing.