Land ships: from this seed many pulp stories may grow...

[Andy in Germany]

"Soviet" means "council", so the council in the front, the nuclear reactor in the back- kinda makes sense 

All are equal, but some are more equal than others...

...and the less equal are back where the reactor is.

[FifteensAway]

I think you're leaning in the right direction - with a little creative amalgamation.  A land omnibus train, a multiple of the tracked omnibus.  And you can even include your steam tank in the mix.  Just don't forget the 'honey' wagon with separate facilities for men and those bolder sorts of women who like adventures.  When you gotta go, you gotta go but when it's sub-freezing outside a proper loo is called for. 

[FramFramson]

Look for old threads by LAF member Colonel O Truth - he made several VSF monsters and was working on an enormous land ship nearly large enough to serve as a table itself (sadly unfinished, like so many other ambitious projects) here: https://leadadventureforum.com/index.php?topic=49200.0