If I figure that greens will be mowed with triplex, I put bunkers about 6' from the green. I also limit green width to a minimum of 50' with 55' preferred because I see the damage done on the edges when a triplex tries to turn any steeper than that, esp. if in conjunction with a small rise. It seems their weight, in combination with any other stress factor, like traffic, poor irrigation coverage, etc. leads to problems.
I recall losing a job once by recommending that we place bunkers 6' from the green edge to accomodate tri-plex "just in case" future conditions (like now) demanded it. A pro designer said by all means, put the bunkers within a few feet of the greens to prevent ever using tri-plex. They bought the high end argument. I wonder if they have second thoughts now. I know I do in making any blanket recommendations!