Do not do full lockouts when doing chest movements, and hit your tri's the same day. This will enable you to keep constant stress on the chest without putting the tri's to work, and be able to train Tri's on the same day.
I work everything twice a week, so I cannot do tri's on a different day. They would not be recovered by the time chest came around again, or vise versa. I do not use lockouts on my pressing, and have had great results in both areas....