The feeds you have don't look bad at all... but he may be getting too much protein from all of those things plus the hay and limited pasture. FeedXL will be able to give you a much more on-point analysis.
Nutrition is a bit of a confusing thing, especially once you focus on age requirements. The most simple question you can ask yourself is "How does he look" If his coat is shiny and he is at a good weight, then you know at least that he isn't struggling and from there you can decide what else he needs. Since he's older it's good to have him on a joint supplement but I've heard somewhere that MSM is the only oral joint supplement that is effective?
It's good to have him on a supplement that supports hoof care, but again.. how do they look? Are they brittle, dry, cracking, or strong?
The highest amount of his diet should be fresh grass and hay. The second largest is grain in multiple small meals, and then you have the supplements.
How much work is he in? Again ask yourself how does he look. He is skinny, is he fat, is his coat lacking luster, does he have rainrot or dry skin, etc. And adjust his calorie intake accordingly.
If he looks fantastic, and doesn't seem to have any problem.. and nothing seems off in his diet, then I believe you have his diet and exercise schedule worked out.
It never hurts after you've got everything nailed down, to check with the vet about a blood panel to make sure he's not deficient or missing anything.
"Strength is the ability to use a muscle without tension"