Mine live at home and get fed twice a day. I am a generous feeder and they eat 3-4 hours a feeding. There is a few hours where their tummies are empty before dinner time (when it’s not grass season) but they seem to survive. If I did free choice hay, I’d have to find much lower quality hay or mine would be obese. My gelding would literally never move from the hay pile if it was there all the time. He also gets 2 large ‘grain’ meals a day so he can get all his GI supplements in.
My gelding is extremely ulcer prone and I personally haven’t had much success with the ‘keep feed in front of them all the time so they never have an empty stomach’ approach to ulcer avoidance. He lives on grass 24/7 in the summer and hardly lifts his head from eating and he still got ulcers last summer (even with his expensive feed/supplement plan). I had him boarded at indoor arena this winter and they fed him a mountain of hay (2 or 3 times what other horses got) because they knew he was ulcer prone. And he still got ulcers.
I don’t like riding on an empty stomach so when I ride in evenings, I toss a flake while I get changed, get my tack out, etc. That gives him something in his belly while riding which does make for happier horses. Then I give rest of feed after I’m done.
Maybe you could give your horse a scoop of alfalfa cubes while you’re tacking up so he isn’t working on an empty stomach?