I was wondering if it was possible to make a flat car load a JR engine. For example: CSX Boxcar Logo ES44AH's without any trucks on the TTX 60ft Flat Car from JR.
Unless it is an international shipment for another country, most new US, Canadian, Mexico locos/railcars would be shipped nationwide, by rail, towed as a dead headed loco.
Not the case, Canada and the U.S. use the same gauge and looky what we have here(not sure why this one is on a flatcar but the second one is because of damage):
Damaged ES44-something, looks like CSX on flatcar due to damage.
Considering the height of a diesel on a flatcar I'd guess they have to be a bit careful when routing it. It might be taller then a hi-cube or double stack car.
Make an interesting consist for Trainz though requiring special routing, priority, etc.
Big job. You'd need to strip down a loco config, change the 'kind', work out attachment points and then do whatever I've forgotten. Is it possible? Probably. Is it easy? Probably not!
Also the 60' TTX flat may not be a strong enough car to do the job, most of your proto pics are heavier duty flats.
Getting OT, but the cribbing under the loads is interesting. The massive steelwork under the CP unit suggests a complete loco minus trucks, the comparatvely lightweight timber under the CSX and Amtrack units suggests totally stripped-out bodies....
Your best bet would be to try to get a locomotive mesh, I believe YukonZoom made his p59s (believe that's what they are?) mesh available, or bdaneal has some mesh's on his site, so that might be something to look at. It should be possible, just make it a load instead of an engine.