After a lot of research on the mii plaza and hacking I've only found two particular things that you can do. For one you can hack a character to have golden pants and become special using the mii editor by GamerDudeK (found over here
https://gbatemp.net/threads/3ds-mii-modifier-computer-utility.396653/).
The second I've only found to work on a japanese 3ds (If you happen to have one). But if you have NTR you can launch the plugin from this website
http://www.speedfly.cn/10282.html. It will give you 9999 tickets and it makes it very easy to get all the headgear. I would love for someone to reverse engineer it and make it available in English.
Other than that I'm not of much more help. I hope someone does find a good solution that we can use.