“gold is too much for many items even in the smallest coin”
Yes, but banks could issue notes based on it, and our mini-republic could either outlaw fractional reserves or open it up to the free market and let banks with varyingly risky loaning policies compete with each other. Bartering would never remain pure barter, anyway, for very long. Soon we’d be batering by proxy, or trading in signifiers of goods, be it warehouse receipts or whatever.
We could use scrip, what are basically IOUs, which actually happened locally in various towns during the Great Depression.
I think it would just be easier to use blank silver coins.
I found a bunch of manufacturers that make unstruck silver coins.
You can get them as blanks for all kinds of coins. As long as you don’t mark the coin, you can effectively trade it instead of using currency.