Even if MKG is available, I'd be skeptical about having a starting wing who is 3-18 on threes for his career. Any deal that involves getting rid of Jeff Green and obtaining his replacement should involve getting a player who is an upgrade on three-point shots. I certainly don't want a starting SF who is a significantly worse perimeter guy than Gerald Wallace.
I think a more realistic trade idea looks like Gerald Henderson and Biyombo for Thornton and Bass. Charlotte needs to include another salary, maybe Jeff Taylor. The Celtics would need to clear a roster spot, probably waiving Dwight Powell. The Celtics should also ask for draft compensation in case Henderson exercises his player option.
If the deal was that the Celtics waive Powell then trade Bass/Thornton for Henderson/Biyombo/Taylor, immediately waive Taylor and possibly re-sign Powell after that, what is the minimum draft considerations, if any, that you would want included by Charlotte to make you agree?