Yes, as stated earlier:
"Yes, a middle bent with tie beam would be good as much to keep the 6x6 plate from bowing out with roof spread (gets worse the lower the pitch) as much as gravity load support. "
You could get by without a true bent, though, by putting a post under the middle of the plate for the gravity load (you probably should include a foundation support under the sill at that post, or beef up the sill), and then doing a tie from plate to plate for the outward thrust. You can see a plate tie in the photo on page 79 of my book. Use long tenons on that tie (5" or through) and offset it from the center post so as not to weaken the plate too much at that point; or use two ties offset a foot or so either side of the center post.