I have found that only part that matters on a vest is the pouches, and even then it doesn't matter as much as the uniform. Your plate carrier/gear make a small part of your bodies outline compared to the uniform. Most of the camouflaging effect is from the uniform to break up your form and blend your body with the environment. The mind when looking at objects doesn't receive 100% of images from the eyes, so it tends to fill in this "blank space" and modern camouflage tries to use this to their advantage. I have found that camouflage is most effective when laying prone/crouching low, so the main thing is cover your head, and your back.
I wear a multicam uniform, so what I do in terms of pouches is just have a tan place carrier (because its cheaper), I have tan pouches on the front (if your enemy is looking at your front, it doesn't matter if you blend in at that point) and I have a multicam camelbak pouch on the back of the plate carrier to help it blend in when laying down. I also wear a multicam boonie hat to hide my face/hair. Multicam helmet/ball cap/whatever would work equally well.
Just my .02!