Yes, LCMs used in the crossing of the Rhine River (March 1945) were painted Olive Drab. The LCMs were transported to the Rhine on trailers behind M26 Dragon Wagons. You can see the results of a number of different modelers in building a Dragon Wagon/LCM-3 combination by searching the net using those key words.
As I recall, one of the the old Time/Life series of books on World War II had a few paragraphs and pictures on the subject.
R/
Matt