I’d suggest cheating and making suitably-sized copies of the piccy at
but these seem to be for the deep wading trunks used in NWE and Italy. From some short googleage, the USMC seem to have used a different system with two cylindrical trunks that look for all the world like 55-gallon oildrums, plus a boxy arrangement on the back. I don’t know which pattern you have in mind, but only seem to be able to find piccies of models with the cylindrical arrangement, no shots of actual vehicles.
All the best,