They say a picture is worth a thousand words, Mike:
It is mounted up higher, snuggled in under the first boat.And basically hidden under the boats.
The rear of the trailer is where the spare tire is.All engines are mounted on the trailer with propellers pointing towards front.2 of the engines are visible at trailer’s rear and were very often packed in protective fabrics to keep dust away:
(BTW this picture was taken in Bulgaria, during March 1941s Wehrmacht crossing of my country in preparation for Operation Marita)
Cheers,
Angel