If anyone does want to try modeling it, I just used an online scale converter and the 1:35 rail gauge would be 10.9 mm. N-scale track is 9 mm, and there is an esoteric narrow gauge railway modeling scale of 09 (O-9), which is used to represent ~18" gauge in O-scale - 1:43.5 in the U.K.
You can get an idea of the proportion of figures to equipment in 09 here:
http://www.youtube.com/watch?v=TRRUSCH4jd8&list=PL31E3EFA3F1AF90E5&index=36This well-done "pizza" layout represents an "estate railway", which the 15" lines were initially proposed / built for in England. (see earlier 15" link)
Another option is TT scale at 1:120, with 12 mm track gauge - not so well known in the west, but quite popular in the former Eastern Bloc and Russia.
Something generically known as Gn15 is widely used for 15" prototypes (and lots of fanciful stuff), with 1:20 - 1:24 figures and details on 16.5 mm track (HO/OO).
It's a bit of a double problem in that as a miniature railway, you want to try to get the rail gauge close to accurate, but at the same time you need to be able to fit 1:35 figures in the engine and wagons.
For a static diorama, perhaps the best option would be to build a new superstructure over a TT wagon chassis for the armored wagons. If you wanted to do the engine, look for a non-running TT-scale 4-8-2 (or close), as you only need a depiction of the running gear, with the armor covering almost everything else. Perhaps a German plane suspended overhead - or on the way down.
Make sure you bring photo documentation with you for the skeptical judges ;-)