Chickened out and just went with the alpha. It has just over 33,000 plys as it stands. That's everything; trucks included. Usually set a limit of 30k for a single locomotive, but this one is two in one. 60k seems reasonable, right? hah.
I know 30k is about right for just the bogeys these days, but I'm still in trs2004 mode. TS2009 at best. Also, it seems I've been trying to catch up on 14+ years of content creation in just a little over a year. At times all of the new tricks and methods seem overwhelming. So, maybe the next one will push 200k(with nary a double sided alpha). Still haven't come to terms with LOD either. Just can't seem to grasp how having 3-5 meshes swapping in and out of memory is better than just one. Maybe I'm missing something.
BTW, I still haven't figured out how to get the alpha channels to show up correctly in the Blender rendering. They look fine in 3d view and export into trainz just great, but they just show up white in the renders.