As a one-time active aeronaut, I can offer some insights about the Chateau de Balleroy.
http://www.chateau-balleroy.com/?lang=en The property was purchased by Forbes, Inc. during the lifetime of the late Malcolm Forbes, and was the base of much of his activity in both hot air and gas balloons. (He set some world ballooning records, btw) There are still major ballooning events held there, as I recall.
It has also been used for world gas and hot air ballooning championships. An annual event was held there for thirty years, but ended in 1999 after Malcolm's death.
TAR has had only one prior task involving ballooning (TAR Family Edition), but this would be the time of year to try for a task related to ballooning (even if it is just having teams go up on a tethered balloon up to an altitude to spot the location for the next route marker clue or task. Untethered hot air balloon "free' flights are flown in the two hours or so after dawn or the two hours or so before sunset as long as surface winds are at 10 mph or lower, and there are no thunderstorms in the vicinity. Tethered flights, which have a tether rope tied (or held down to the ground) can take place as long as the winds stay low enough or are calm.)
If the maze is on the Chateau property, then a task with both almost jumps out at you. And the fact that the Chateau is closed at exactly this time? Well, let's just say I don't believe in coincidences.
It may not be, but I would not be surprised if it is.....