I have a problem when I have a single train on the same network as a normal one, using LTN. LTN can't seem to differentiate between a single train (which seems to come out as length 3, and a normal train made up of two engines, which also comes out as length 3. So it ends up sending a train to a station which isn't configured for it's length.
This is only a problem if you mix trains on the same network, but would be good if you could change the "length" of the train so we can restrict the stations to trains which are appropriately configured.

A single train unit is made up of 2 very short locos and a very short wagon within the game. Its just these parts are hidden from the player to give the appearance of a single thing. So yes LTN will mis read it as a dual headed 1-1-1 train by default.

I don't think there is anything I can do from within my mod to help LTN. All I can think of is that LTN would have to look at the train it is querying and recognising the train parts by name. Although I wouldn't expect you'd want LTN to treat a single train unit the same as a single locomotive or a dual headed locomotive and 1 cargo wagon train. It would need LTN to put it in its own special category to handle the size and length differences.