Sounds mostly lovely, the only thing I'm a bit :/ over is the "no online payments" part. Not even because it's hard for the players - just fun and different, mostly - but because it'll be difficult for you to handle. Imagine getting letters with bills in 47 different currencies...
EDIT: This is a bit weird, how this post is presented through the itch.io forums - as an indented reply of some sort... This'll take a bit getting used to!