Real Logistics

What do you think about needing to build transport ships/trucks for trade? Rather than the market being a magical and "instant" thing players would work out a deal and need to physically ship the goods and receive compensation. Possibly transporting goods from resource provinces to the trading port (boarder province or harbor). This would provide another use for the navy protecting sea trade routes and require serious diplomatic relations when routes are mixed together (like the mediterranean). This could also promote economic alliances that simply are not required in the game as it is.