For all intents and purposes, my home course is now the Windsor Golf Club in Windsor, CA. There is an interesting spot behind the third green, a shortish par four that I've been able to get within 30 yards of off the tee. Because it is such a short second shot, it's not unusual for a player to blade one over the green. Behind the green, which runs roughly east-west in kind of a banana shape, is a boundary fence roughly ten yards behind the green. Just before the fence is a cart path. Here's a look at it from the middle of the green:
You can see that there is not a lot of room between the cart path and the fence. Here is a better view, from the side:
It may not look like it, but there is actually room to drop on that grass strip behind the cart path and have full relief from the path. However, if you did that, you would be in a position where your back swing would be impacted by the boundary fence, and, of course, there is no free relief from a boundary fence. If you took this relief from the path, then wanted relief from the fence, you would have to declare an unplayable lie and take a stroke penalty. As the path runs parallel to the width of the green, you would probably not be able to go two club-lengths either direction without (a) getting any closer to the hole, or (b) improving your situation to the point where you would actually have a clear swing.
The alternative would be stroke and distance-- go back and play from as close as possible to the spot where you hit the previous shot, the one that ended up on the cart path. After further review, we decided that the best course of action would probably be to play it off the cart path. After all, whose wedges aren't already pretty scuffed up?
As a second year TO, I found this an interesting situation. It underscores the need to make sure players are aware of their options BEFORE they pick up their ball. It's the reason one of the senior officials one told me that the last thing you want to see when you arrive at a situation is the player with his ball in his hand.