^ To me, and I am by no means educated on halter showing and/or anything beyond the very most basic aspects of such, so I am simply commenting to add that, IMO, hard work is an awesome challenge which can be embraced and can lead to some really awesome quality time between you and your young one, there!
I HAVE to adamantly agree with GH regarding sweet feed. (I know you already decided against utilizing such, so do not feel I am trying to further "convince" you!) however, as recently as 15 years ago, all of the horses where I worked were given sweet feed, it was simply "the norm". Coming back to the horse-world after 15 years, I have been re-educating myself on equine nutrition and the like. What I have learned is that sweet feed and most any form of oat/"cereal" grain has been found to be non-adventitious in all ways to horses...who knew??:0)
I guess, in the days of horses pulling carriages as a means for humans to get around, such as recently before the invention of the auto, keepers discovered horses liked and could "digest" cereals, thus, they fed what they had handy in cities in greatest quantities, in addition to forage of course, & this became commonplace. Much more to it than that, but that is just a basic summing up of where grains and horses "connected" on the larger, common-place scale.
Recently, however, it has been found that cereal grains are the cause of over 20 previously non-understood equine dietary/other nutritionally based problems and basic concerns of previously unknown etiology. Bottom line: grains are not only often nutritionally lacking, but NOT the sort of foodstuffs which horses were meant to consume. I'm really not on a soapbox, and there are obviously much WORSE THINGS one can do with ones animals than to feed them grains! I am not intending to project that...I suppose having recently been studying equine dietary need, I am hyperfocused on this topic, and find it fascinating, as, had I NOT happened to begin learning about this, I would be the FIRST to say, based on ask of the experiences from my youth, -"Hey man, horses EAT GRAIN! That's the way it is!" So please don't take my comments as preachy...do look into it, however, if you like. It's truly fascinating!
Anyway, absolute best of luck to you and your horse in your endeavors. He is beautiful!!
"I'm too busy working on my own grass to notice if yours is greener"