It's confusing, one advantage is we have a mexican base and access to a lot of officials. Doing mexico city tours out of Teotihuacan is a lot easier than out of Puebla. It would be nice if they published a clear map with a boundary line. Seems to me the possible way to do it is to arrive on a sunday when there is no problem and look for the closest parking spot outside the boundary to park til light and leave San juan at 4:30 AM. The boundary cannot be far away. Passes are OK but with a group there may be a few too many with rigs over 15 years old. however most RV & truck plates do seem to end in a letter.