How about introducing a second type of Supply Ship that transports military production to a shipyard instead of social production to a planet?
In my ludicrous games there is always the situation that newly colonized / conquered / small planets are quite bad at military production. Channelling their military production to another, existing shipyard is no option most of the time because of distance decay, so they end up each with their own shipyard that produces small ships or Treasure Hunt missions since large ships need forever. If I would be able to transport the military production elsewhere by means of special supply ships that problem would be solved (and new tactical decisions would arise. e. g. like where to send the production and whether to escort the supply ships).
It would be nice if there would be more than one size of supply ships (that's also a wish that I would have for existing supply ships), especially smaller and therefore cheaper ships would be good.