Hello Andrew, Is impossible to say how many covers from Guatemala were carried by the Hindenburg on each North American flight. Some years ago I published an article in "El Quetzal" and I destroyed the myth of "50" Guatemalan covers carried on the first North American flight, and established the rate charged in Guatemala. The number "50" is the number listed in Sieger & Michel Catalogs for the first North American flight. Before writing my article I wrote to the Sieger Company in Germany, and I received a letter signed by Elsbeth Sieger (I have the letter on my hands), mentioning that the catalog started to be printed in 1922, and since then the number "50" has been mentioned. All the records from the Sieger Company were destroyed during WWII.
I know about a Guatemalan cover carried on the 10 North American flight that is on sale at a bargain price: 1,200 euros!. I have the Michel Zeppelin catalog in my office. I will check tomorrow if they mention something about it. Regards Gabriel