We had an interesting situation at the 1996 U.S. Junior Amateur at Forest Highlands where the homeowners agreed to keep their houses in play, so there was no out of bounds. (For those not familiar with the Canyon Course, there are houses on the majority of the holes and several roads to cross.) If a player's ball wound up against a house, he would take immovable obstruction relief just as he would from a rain shelter.
It worked well, except for one anxious moment when a player had to play a pitch shot over a parked Cadillac (whose driver was not to be found)!