If the trains only come 2x a week why don't the 'new owners' allow people to modify a truck so it rides the rails and can pull a couple of containers that have some wheels put under them?
Clay and water is not a good base for a set of rails to ride on. Today they make all kinds of waterproof road building fabrics that could be used to wrap the clay so it does not get wet and float away. A drilling lease can put down some of the cheaper stuff and 1m of clay and if it doesn't rain you can drive heavy loads.
Why could the peat not be dredged and pressed into a form that has little water in it and some ' industrial tote bags' could be used under the fabric so you have some cheap filler that will hold up the road until it is 'stabilized'. Even running a steel cable in the fill that is used for the sub-base can be made into a grid that hold together over what is almost a 'shallow lake'.
The more north you go it might be easier to install some pipes that go into the permafrost and bring the cold up and have some foam where the fabric is so the part below does not melt. That might also be the best way to build a house also, install some transfer tubes and some foam laid on the ground and the house on top of that and the frozen ground is stable year round. Trailers could be the same, insulate the skirting (earth berm would work) and the floor of the trailer and it will be a freezer year round so no insects under there and the need for a fridge and freezer is eliminated.
Dried peat must have some sort of R-Value.
Mixing flax straw and adding a small amount of cement powder would result in something (soil cement) almost waterproof and the straw adds strength. The ballast rock should be caged in wire like in all places where fast moving water is possible
https://en.wikipedia.org/wiki/Port_of_Churchill
The port is iced in for much of the year and is accessible only between late July and early November.
[4] For example, in 2010 the shipping season was July 28 to Nov. 2.
[6] Shallow waters also restrict its development as an ocean port. Despite these restrictions
the port remains useful for shipping grain and other bulk cargos because shipping by rail costs several times as much, per ton, as shipping by sea.
If grain is shipped that is not a cargo that brings any goods to the Communities if it is shipped out. There are enough grain terminals for export. Perhaps the storage can be used for what the residents in the north can use and local boats can do the deliveries. Grain might be better than ready made flour so some easy way to grind it at home with something electric powered means there is no waste, or less waste which is almost as good.
I still think feeding fish is possible on a commercial scale summer and winter because no foreign boats can sneak in and take the fish. That is another use for the grain storage.
If aluminum rail cars $exist$ how about composite fiber ones right down to the wheels holding a titanium contact ring. At what point can they be made to have electric drive wheels so the heavy engine is not needed?
The rail line looks like only solid ground so the power lines should be run above the trains on their own tower and that just begs for ultra high speed electric people movers should anyone ever want to get to Winnipeg in a hurry, ever, being the key word.