OTOH, if its portside, that means that one time advantage of trucks is offset by doing ship loading/unloading directly from/onto the train.
So a grid of "Steel Interstate" model corridors that all end at a port would seem to be the most promising basic model.
If the the passenger trains are going at least 175kph, its hard to see why they'd have to go faster.
If only the standard gauge turn-outs have to be high speed turn-outs, it seems like it'd be possible to dual-gauge the track in intermediate stretches and switch out to a dedicated standard gauge section for crossing and passing loops and stretches with a larger number of turn-outs per km. Common right rail if the typical standard gauge passing loop is passing to the right. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.