In most cases, shouldn't the back tee be placed for the top, say, 5% of golfers or something, similar to front tee being placed for the shortest 5% of golfers? I understand and agree that design strategy (and tee relationship to previous green) should focus on those middle tees that most golfers will be using somewhere in that 6400-6800 range, but unless the site doesn't allow such, why shouldn't there be a back tee at 7000-7300 on those courses unless it is hard enough already?
For the record, I have always had muni courses as my "home" course and have rarely seen people playing the tips that shouldn't. It seems way more common to me for the high handicapper to move up to the middle tees regardless of the length they play, not the other way around.
Jeff, as an aside, I think your course Highlands in Lincoln, Nebraska has a pretty nifty way of discouraging regular play from the "tips". As one of the four muni courses in Lincoln, it is the only one with four sets of tees (the others have three) and is significantly longer than the other courses at 7000 yards. The other three courses go black (tips), blue (middle) and white (front) tees. Highlands has those three and adds gold tees to the back. I have played back there once or twice at a 9 handicap, but I'm not sure I've ever seen anyone else back there before.