Personally I'd leave it in Neutral only because no matter how secure the car is strapped down, it will still rock forward and backwards. This put an enormous strain on the "Park" gear within the automatic transaxle.
[SIGPIC][/SIGPIC]2016 Newmar Dutch Star 4369
Newmar Owners Club
USAF 1966-1969,- Law Enforcement 1969 - 2003, Retired since March 2003