I had not thought of the Thundershirt... that sounds good.
Any ideas on introducing him into our "new" RV? We restored a 1965 travel trailer and added an airconditioner. We turned it on last week (without the dog in there) and realized that it is just as loud as the one in my parents RV so we are concerned for him. There is only 1 speed for heat and low/high for air conditioning. There is NO doubt that it is running

.
I may order the Thundershirt and also give him a few treats in there, but I'm open to any ideas on getting him acclimated.
Thanks for the Thundershirt idea!!