Military Olive? Hi!, H.A.
I used to think as a kid that Green Olives were for Soldiers! Kidthink, don't ya love it? The thing is O.D. and it's many iterations did not stand up well to the conditions over there. A nice Olive seat cushion would be a sickly Grey/Ashy/Green with some Canvas natural color showing through by the end of a tour.
Fabrics suffered from "Jungle Rot" very quickly. the Humidity, Heat, Monsoon Season all took their toll very fast.I would say if you stick to the colors I mentioned, mixed together on the same cushion or fabric you'd be just fine. Don't forget to put in some ground in Deep red stains from the mud that was self evident too. Once it got on your clothes and equipment it weren't green no more! It acted just like Sandpaper!