Noone knows, when horsecarts will apear. I think people are really anxious to see at least somekind of a solution for cargo transport. So, why not implement a model of a horse with a saddlebag? It will have a model of a basic non-combat horse, but with saddlebags at sides. So, people will have to craft a special item called sadlebags, put it and an untamed horse inside the training field, like with a heavy warhorse. This horse can be slighly slower than a normal untamed horse, but will have a storage capacity of 600 stones or something. Its storage can be accessed via right click on horse->basic actions->Show inventory. This horse will have the weight of a simple horse, so in order to prevent capacity abusing, all the items inside the horse will dissapear after you take the horse inside your inventory\warehouse\etc.