No, the MTS in SCARM will not simulate physically caused derailments, such as excessive speed. I like the line from the Star Wars spoof, "ludicrous speed". A scale 60mph will be ok on O72 curves and up, but it will look way too fast.
The realization of the scale of 1:48 layouts is one that we all experience. Most layouts in O compromise or compress elements. You have the right idea, sizing a train and platform so that it appears correct, not necessarily to scale.
perhaps in your town, there isn't enough passenger demand. The crew knows this and stops with the designated cars in the proper position.
The peninsulas are the change direction features on the track plan. Place a passenger station in each of those. The train departs, makes a few long runs around the room and the changes back to inside track and enters a peninsula to drop passengers and collect new. Then, it departs in the opposite direction, runs some laps and does the same on the other side. Manage the freight traffic accordingly.
You have enough space to add in sidings for operational needs.
The collaboration of ideas to get you to this point has provided a "Backbone". You can study real railroad operations to get ideas or just make-up scenarios that you like. Then, add the required passing siding(s) or spurs. This is the operational part of designing a layout that adds the play value to suit you.
Running two trains on this track plan in simulation and then viewing the elapsed time will provide some guidance on how long a run session will last.
Developing this fine tuning is very personal. I would recommend that you build this and find what is lacking. Many of us could add elements of operation from our experience. That may not be what you will like when you actually get into some run sessions.
Building this will be a task that you will be able to accomplish and still have fun with it. There is plenty to be done to make this a reality.
