If it was made where once you got a piece of the set, it becomes not able to be looted then maybe you could get a set or at least a mix and match set. Would be super hard to get, but I'm assuming possible as long as the set could be dropped anywhere like El Patron and Silver Freeze. Once say "hat" was obtained just make it so "hat" is not unlocked so you can't loot it again. Then the next time you got a legendary clothing it would be something other than "hat" like "pants". Otherwise you'd have people with 3 hats and nothing else, but that would in itself be extremely lucky, whereas if they stopped being available as you got them 3 legendary clothing would be something like hat, shirt, pants. Would work like "do you have 25 tonics?" if not get a tonic, if yes you can't -- but for each legendary clothing.