Hi Ghost,
Have been reading some of the comments.
Well 1. Riding lights /anchor lights , vessels under 50m one forward all round not lower than 15ft off the deck. Over 50m a second light all round is fitted and it must be lower than the forward light.
2. Your intended markings for the stern is correct, although it is not compulsory on the bridge top. I do not have access to an IMO code book But I believe there is a number in the beginning for the country of reg like phone numbers have.
3. Special operation lights would probably be okay for towing a sonar. When I was on trial ships in the past we only put on special op lights for towing noise makers several hundred yards astern of us.
4. Towing lights are compulsory if you are towing something on the surface, some such as large fresh water bags have a special light on the tow, used to be seem quite regular in the Med.
Apart from that mate do not get to fret up over details mate, just enjoy your model, I think you are doing great. One way of looking at it is too much detail leads to more broken bits when you run her and at the end of the day when she is over 3foot out in the pond who will see them. People like you give me encouragement as I am lousy with my hands, I am half way through with a half scale PAS tug Energetic, but I expect the rivet counters will pull it apart, but that is live who cares, your boat looks great mate.
David