You can do it without any problems. Lots of grain shipped internationally this way. Just think it through. First, you have to build a bulkhead to separate the grain from the doors. You can buy them or build your own. Commercial ones are nothing but a few 2”x6”s and some cardboard. Plywood will last for years. For repeated use, drop in a false floor, 2”x4” on edge covered with perforated sheeting.  You can also use perforated pipe. Perforated sewer & drain pipe covered with infiltration fabric will also work. If you are feeding the grain and use last in, first out, no need for aeration. The height of the bulkhead is determined by the filling mechanism. Pros will use a horizontal belt conveyor fed by a tank, auger, etc. A long auger will also work. The bigger (deeper) your filling system is, the shorter your bulkhead has to be. Or, if you have a lot to do, you just build a tilting mechanism for the entire container. You need an aeration fan and plenum with several opening – for a tubing run to each container.  One 12” bin aeration fan can handle several containers. Or buy a small 6” or 8” fan and switch it between containers. If you do this, make sure that the fan can produce enough positive pressure to insure minimum aeration capacity.