NTBF – New buildings for the towns in Tribes of the East 3.1.

Sending units and heroes to work is a great idea!

In my old mod, I had an idea: if you leave units in mines, they generate additional income.
And, when you place a warehouse or upgrade it, you can upgrade the mines on the map.

Added 1 minute ago

I didn't even think about veiling, but adding something new and not entirely standard is a good idea.
And for treasure chests, you could offer artifacts as collateral for additional resources per day. It's a bit rough.

Additional dialogue load. And collateral isn't necessary – you can just sell the artifacts.