The boxcar weights I'm messing with are part of a new weight change scale for RT3 1.05 and 1.06. Boxcars are what some stuff will be shipped in before the late 20th century, but for game engine purposes it's only a car designation. The "boxcar" can easily be modelled and skinned as COFC or well cars or whatever for the late 20th century onwards. I'd already thought of similar ideas to the ones you suggested, and have a few other things stashed in Blender.
TOFC is frankly too much bother to model for not enough benefit, IMHO. I'd rather do other things.
Edit: By the way, just so you know, the limitation with RT3 is lumps in track. Unless the map is absolutely dead flat (hardly any are) you are going to have lumpy track somewhere. Multiple units won't flex over lumps. They'll bend horizontally around corners just fine, but they won't bend vertically at all over lumps. The entire wheelbase of each RT3 car load (no matter how it's skinned up) is dead straight rigid in the vertical direction.
Basically anything over about 100 RT3 units (83 feet or so to scale) starts to look too bad, too often. So really this is what stops us going nuts with Gunderson MAXI-IV's and stuff like that. A MAXI-IV would actually be pretty easy to model and skin, but unfortunately it would look utterly terrible a lot of the time on most maps.
