Fake coins could be a lot of fun at a table, but if it's 1:1 the actual gold given in the game, some quests could call for a lot of those and it could get a littler ridiculous!
I have some round cardboard tokens that are kind of fake coins... one says "mercenary" on it and I was using as a merc token, the other has the image of the person I still consider to be the likeness of Zargon on it, used for elite bad guys and as a turn marker for the evil wizard player. I presume the money of the Empire would probably resemble something from the Holy Roman Empire or inspired by that, a small gold coin. As I was looking I found a news article from a few days ago about a hidden cache of Byzantine coins
here. Who says buried treasure isn't real?
Anyway, many ways to enhance the experience, I hope you find one that works! Maybe like one coin represents a certain amount of gold or something... because your hero could be carrying 500-1000 (usually at that point you'll start spending it) after just a few quests.