TBH, that's more Vicky territory, and it is probably wise to keep it that way. Apparently, the Vicky II devs get a fit whenever regional markets are even mentioned.
To be a bit heretical: wouldn't it be better to get rid of trade goods tied to provinces? ATM, there are some arbitrary boni for having access to certain trade goods, but that's pretty minor. Some events are influenced by trade goods, so what. The biggest differences is the production value and the trade value, which feed money into investment (or minting).
Instead, incorporate some of it into the base tax (i.e.roduction) and cover trade by collecting tolls. Which of course, would demand a different trade system, but that we need anyway.