I find that beet pulp helps too, seems to put weight on in the right places.
I've fed a higher fat in the past too for weight, coat & condition. I went to a seminar last weekend on a new feed, and their entire premise is different from anything I've heard. They maintain the fat is not in fact healthy, and that it hinders performance. It's a highly digestible extruded feed that is only 2% fat and yet, everyone I've heard from who feeds it says the horses will put on weight and look terrific with it because in part it's so completely digestible. It's aussielogic.com if anyone is interested. I have 4 horses here on it to test, will see how they act/look in a month or so.
Jan