Should have hired a valet for the weekend. That way they could double park and stack cars as needed and have all the keys to move them.

Other option would have been for them to arrange with one of the nearby lots and maybe give "permits" to put on on the dash so you were guaranteed not to be towed.

I'm actually in a hotel right now that has tight parking because of a huge number of restaurants in the area and they have a valet all the time.

When my office building in Atlanta was having their parking lot completely redone, they hired a couple of valets and when you were parking in the morning they would ask when you were going to leave and park accordingly. I was a late worker so my car always got put pretty deep into the lot whereas if you were only staying for an hour for an appointment or going out to lunch or something they would put you over on the side so they can get you out fast. It took a couple months to rebuild the lot so it actually worked quite well.