Questions on authority & protection on RR operating 1 train at any given time

Hi all – this is my first time posting here. I need some tips on designing a set of operating rules for a pet project of mine. Though it’s a model, some prototypical input is greatly needed! Here’s what I’m modeling (don’t laugh) – a narrow-gauge VERY short line, akin to a steam dummy, whose entire roster of equipment consists of two locomotives, and one each combination car, boxcar, flatcar, and bobber caboose (mostly just for kicks). Naturally there is only one crew, and the line operates four mixed trains daily except Sunday. There is a telephone line along the RR, but the only communicating stations are the two termini. Clearly an elaborate system of authority and protection is not required, and it’s likely that any such railroad in real life would have only very basic operating rules, if any, with very little formality. But I would like to write up a rulebook that is as thorough as you can get, without being needlessly complex. The one time I can imagine flag protection and restricted speed might be required would be if the mixed broke down out on the road, and the engine crew (leaving the engine under the supervision of some competent trainman, I guess) would have to trek back “into town” to fire up the second one to retrieve the first. We’ll consider this to be in the timetable-and-train-order era of operations. So here are my big questions:

  1. In the scenario described above (breakdown, need to fetch second engine), would you provide flag protection for the train on the main? Federal law these days sez it’s not required when a RR operates only one train at any given time, but then the old rules say, “an engine without cars in service on the road is considered a train…”

  2. Would the above scenario be handled instead in special instructions?

  3. Would restricted speed be required on the part of the engine going to assist? (Or in the parlance of the era I’m modeling, "proceed with caution at slow speed, prepared to stop