Besides good management the best prevention against Laminitis is L94 (or P45 which is L94 and Magnesium) especially when it is imperative that the condition must be avoided at all costs
Obviously if it cannot be afforded then that is the end of the matter and other ways must be sought to lessen the likelihood of an incident but in defense of the cost of L94 you do know what it is going to cost and can make a decision. Alternative calculations can in truth be far less expensive but at most a nightmare with call outs etc. Depending on the quality of the grass the grazing still has to be considered to limit excess weight in some inactive ponies but at least the misery of muzzles and starvation compounds can go and both you and the horses and ponies are happier.