Yeah you are right about the correctness/ tone of the colors.
I think it's important to keep it the same tone.
Which IMHO for the American is 'Vietnam war' camo green that you see on their helmets...
Other than the rear cover, I think the rest of the green and brown on the bike is still matching.
Anyways I could probably con the youngsters these days that the rear wheel cover design is similar to those camo nets they use to hide tanks from aircraft in those days hahaha... In fact after lookng at it now, I think it is!
Can't really find these big patch camo colors in the military these days, mostly camo splashes or going 'digital' like the Singapore army below: