I have been working on and dealing with engines enough to look at what you report, and think there is a problem. If my engine where doing what yours was, I would be getting similar results and dirty oil... I do not have to do climbs, and every type of riding imaginable in Evey temperature on earth to know when an engine is burning more oil than it should, and to know when the oil is getting prematurely dirty.That's a fast conclusion...you have a lot to take into consideration. Rider weight, how long at wot, how long of a day with the oil at temperature, flat ground or uphill battles, and there's more. A lot of groms I have ridden with have also consumed close to the same amount of oil as me when we go on long rides
I know you do not want to face it, but I think you have a problem with your engine. Not a huge problem, but an annoying one that will cause you to add and change oil more often.