Sorry, I am about to make things worse. The Romans started the Dolaucothi gold mine in Carmarthenshire, which are still in production. I would think the infrastructure required for this, including aqueducts and waterwheels, and mills, would suggest something more settled than a military occupation. Perhaps you better reinstate Wales, though I’m not convinced most of it was subdued, but you really don’t set up a gold mine if surrounded by truculent inhabitants, I should have thought.