Multi-use Skytrain, i.e., move goods between suburbs and downtown/port via Skytrain

Moving goods between the suburbs and Vancouver/the port has a significant impact on our roadway infrastructure, burns fossil fuels, contributes to traffic congestion, etc.  What would it take to retrofit the Skytrain system (cars and stations) to allow movement of goods?  Goods transport could occur either after the commuter trains stop running, or during the day between commuter trains. 

Am I crazy?