That is not a battlefield, and she was not really participating in training. There would have no need for her to wear camouflage make-up.
And if she is anything like me, she might look rather tired and pale without make-up. Not everybody rocks the fresh face.
Those pictures however will go around and if she looked anything but "her usual pretty" people might either think she was sickly or not really liking her day at the camp. Both not good options.
I agree. The same with big blue. If the ring is missing it would start rumors. I think she looked fine, except the pants were too tight. They are actually of heavy material with french seams, they do have pockets and were probably warm enough but Just a bit too tight for me.
She did have her hair held out of the way, and she was properly dressed for the engagement and weather.
Kate was interested, hands on when needful and attentive. A good first outing for her and the Irish Guards,