I tried bark one time, it cracked and made the bow fail,, so I did not try that anymore,,once bit ,, twice shy,,,
as far as chasing a ring,, I am sure there were variations on that as well,, I feel like a bow could be drawn further with one ring on the back,, I have a bow here that a friend made with very very thin rings,, he left the sapwood on the back and it is very violated,, never broke,, overstrained the bow so hard that it fretted the belly,,Osage,,, but the back held,, sorry bout the ramble but,,,I plan to sinew back it,, scrape out all the frets and see what it does,,,leaving the sap wood back as it is,,