How do you use your horse? For trail riding, or do you show? I would limit anything containing alfalfa hay, which will only make him more susceptible to laminitis. Same with the grain. Very rarely does a trail horse need grain. Having said that, you’re right–you don’t want to turn him out in a field where he can eat grass all day long. Are you available to turn him out for short periods of time to graze and then return him to his stall?