I guess you could say that Florida only has one sized tag ... but do the motorcycles in your state have full sized tags?
We had a tag go missing. After filing the police report, the tag was replaced free. When we were getting the tag we asked if it possible to get a "motorcycle sized tag" for the trailer. They said yes. Actually, I found that the motorcycle tags have their own numbering sequence, so what they do is "re-assign" a motorcycle tag for your trailer.
So, even though all the "auto/trailer" tags are the same size, motorcycles have smaller tags. Just ask ... you may be surprised.
As for the placement, we fastened the new smaller tag to the back of the left fender with screws. No problem with drilling 4 holes for the tag here. Seems to me, the risk of the holes is way less then the risk of the ticket for not having a tag - or not haveing a "legible" tag.