I would not worry too much about it. The rivets that hold the skins onto the ribs conduct so much heat that the tape makes little difference. Years ago, in grad school, I worked at a "thermal lab" where we tested things. One interesting article I read then made a great impression on me. They had a one foot square piece of a curtain wall material used in big buildings. Aluminum glued on each side of a 2" insulating material. To keep the aluminum from coming off in case of a fire, they tested having a single metal connection between the inner and outer skins. When tested thermally, the single 1/4" diameter metal connection from inside to outside doubled the heat loss or gain of the one square foot panel.
In a similar manner, the rivets which hold the skins to the ribs of the Airstream overwhelm the thermal tape. It is not bad that it is used, just that it really does not help a lot.