For other readers’ reference, this was my suggestion from last year: IDEA: alternative to Tribal Market for Lakota/Haudenosaunee
These days I find it too convoluted & reliant on the whole “wagons can become anything” idea. Would rather suggest replacing the 50-wood Marketplace with an ability to convert expired treasure spots into fur camps (limited coin deposits, same graphics as Marketplace, neutral & gatherable by any Lakota/Haud vill but no other civs), meaning the player gets to skin the animals they just trapped or slayed, and use the site to capture more animals.
The ability may have additional limitations, e.g. can only be used on spots without human guardians - obviously you trap fur at places that attract animals, not humans (also mirroring DE War Chiefs’ different mechanical solutions for animal/human guardians). Amounts of a deposit can be flexible to ensure balance, e.g. adjusted by map size, total number of treasures, on top of guardian difficulty. Needless to say, a player’s starting mine & fur den are replaced by a special fur den that turns into a camp with standard starting coin.
It’s a far more radical gameplay change, but also more logical and less arbitrary.
(Yeah, maybe the coin techs also add very slow coin gather rates to hunts.)