I wouldn't worry too much about staying over the 3 hour limit when pool hopping. We have gotten several of the 3 hour passes at the Poly. I have not heard of anyone actually having their vehicle towed from the lot. If you are that concerned about it, just park at the MK lot and walk to the Poly. I doubt many legitimate PHrs will exceed the 3 hour limit. The biggest issue is if the resort is packed and you are keeping a legitimate resort guest from having a parking space while you are dining or pool hopping. That is Disney's problem as long as you are following their guidelines.