In order to instantly load the ship you need to do the following:
1.- Create a caravan from the world map (vanilla) with all the objects you want to take and/or slaves, leave 1 of your pawns on the map along with the ship
2.- Send the caravan to the world, it will not be able to move due to the weight, but that does not matter
3.- Send your pawn in the ship to the same yellow point where your other caravan is and click "Form caravan here"
4.- Merge the caravans
5.- Launch the ship
6.- Enjoy all the loot from those RimCities!!!