Mark:
If PV does add a new tee where proposed on #4 that would probably pretty much max out the course distance-wise, although there probably is some avaiable elasticity here and there on holes where it wouldn't really make much sense or matter. Obviously with tee length addition one has to consider if it's remotely possible hole per hole given what the hole is all about and it certainly isn't possible and basically never been on #2, #5!!, #6!!(they did add the Jay Sigel tee years ago), #10 (they did add some here less than ten years ago, #11!! #12 (the back tee here was added by JAB). Some of the others were maxed out in the last few years like #3, #7, #9, #13, #14, #15, probably #16 and #18. Somebody told me they might consider adding to #1 but I can't imagine that because if you took the vegetation away a new tee there would almost hang out over the driveway. They could probably add to #8 and frankly it looked to me recently like that just regraded that whole tee and maybe they did add some to it. But if they do end up doing #4 that will put the tips around 7,050 which is pretty good for a par 70 course that has 2-3 really good short par 4s on it.
But obviously no one in their right mind would consider adding anything to #5 and it isn't necessary anyway. They have very rarely ever used the back 1/3 of that tee anyway.
One hole they actually could add to bigtime is #17 and it was very lightly considered but it would seem to me to have been pretty odd. They could've gone way back behind the waterworks which the present tip tees have always backed up on. The interesting thing about #17 is one of Crump's initial iterations had that hole quite a bit longer than it has always been. The reason for that is Crump was considering the 16th as the par 5 with a green probably out near the peninsula behind #14. From there it would have been a short stretch to the left to a much longer #17 to a tee that obviously would've been behind the water works.
Also, believe it or not Crump had been considering putting a tee where the new #9 tip is now and also sort of near where the new #13 tip is now (he actually wanted something of a ramp off the back of #12 to the tip 13th tee).