You forgot the best available (RFA) stretch 4 - Nemanja Bjelica.
I know Bjelica played a stretch 4 but he's truely at his best as a massive 3 man, he's always been that until he came to the NBA when Jimmy Butler went down he played the 3 very effectively like a Joe Ingles (less handles than Joe) the guy is a excellent playmaker and is a 3 man forced to play the 4 for some reason (Thibs not known for his flexibility). Every time he played the 3 he was a really solid NBA player at the four he sucked imo. The Wolves colour commentary guy (Peterson?) always even said the same thing that Nemanja is at his best as a 3.
I would love Bjelica as a back up 3 man all day every day who can at least slide to the 4.