It looks like a pretty old topic but it's new to me - I can't see clearly from the photos where you tie the 11th string on the bridge.
I can see that the bone saddle is longer and notched but the string must come from somewhere. (The overextending bone nut is an accepted practice among lutenists.)
Does this solution work?
I'm quite interested (as I have a 7-string guitar and a 11-course lute and I'm planning to buy a 10-string guitar), but I'm afraid the quoted site is not available any more.
Your playing is very enjoyable, by the way, those deep basses are what I like about multistring instruments. And Weiss is the greatest for the baroque lute, of course. I tune down mine to low G' or A' and enjoy the low register very much.
Music to hear, why hear'st thou music sadly?
Sweets with sweets war not, joy delights in joy...
William Shakespeare, Sonnet 8