Not sure if this will be of any help but it occurred to me that in most monograms the middle letter is usually the first letter of the last name and it is always largest. John Quincy Adams would be J <span style="font-size: 12pt"> A</span> Q
So maybe you are looking for the initials SHJ OR maybe even SHTJ...the large center character "might" be a combined T and J?
Think also of clubs...country clubs, golf clubs, yacht clubs, private condos or developments...places where you are a member or registered owner, etc. Some place where the front gate would recognize the sticker/number and let you in.
<later that same night> Ok, so I typed "sjh member" into Google and came up with Metropolitan State University - Saint Paul , Minneapolis and they have a St. Johns Hall on their Saint Paul campus. Something like that would be appropriate of that type of sticker....