I think the bow will take less set if you use a pulley ,, or dont let it stay drawn on the tree,,
hard for me to tell with a photo but seems to be bending a bit to much out of the handle,,maybe make the outer mids work just a bit more,,
what does the unbraced profile look like,, that will give you the info you need as far as how the bow is taking set now,, if it is not taking set now your tiller is pretty good,,