I have worked some more with Trip, trying to spend time with him each day. He still wants to chase the lambs. I put the sheep in their night pen, Trip in the pasture. In the mornings and evenings I let him out to play with Parker, our big black Lab/Great Dane cross. They run laps, tussle and chew on each other, exactly what Trip wants to do to the sheep. Trip runs off energy and is ready to go back in the pasture.
Today I was watching the sheep and Trip, when Sheepalicious was trying to eat some high branches of elm. She tried standing on a pine log, but kept slipping off. She came straight to me, baa-ing, clearly wanting me to do something. So I bent the branch down and all the sheep stripped the leaves off. I walked around for an hour bending branches down to their reach. Trip circled the pasture and watched the sheep, he behaved himself fairly well. I did have to call him down several times for getting a little too up close and personal.
So for now, the sheep spend the night in their night pen and Trip in the pasture. During the day, Trip is in the night pen and the sheep in the pasture.