but there is still muddle as to whether it is equivalent of gauge 2 or gauge 3 (IIm or IIIm,to use terminology used by some)
In Germany and large part of Continental Europe the number 2, sometimes written in Roman II
stands for model railroads in a scale of 1 : 22,5. If followed by a letter, like m, g or f it stands for the the prototype gauge, e.G. IIm (2m) for Metergauge, g for 750/760 mm and f for 600mm / 2 feet. They even tried to establish IIp for 381mm / 15 feet. The p stands for Park-Eisenbahn. they had a few of those and still have in some parts of Germany.
"G" does not stand for a scale. It simply says, it will run on 45mm modeltrack. "G" was invented by the trade, to fool unexperienced customers. A lot of "G-scale" stuff combines various scales in a single model resulting in offerings completly out of shape.
The Gn15 inventors, Steve Warrington and Steve Bennett 15 years ago, originally claimed, that Gn15 was in 1 : 22,5. For the majority of today modellers, it seems to be in 1 : 24.
Returning to the V-skips. Of course the Decauville 400mm gauge types were intended to be pushed
by hand. Never heard of a loco with 400mm gauge. Still no reason why such a thing should not excist.

Decauville, 400mm at Valkenbourg Meseum, NL
The seize of rolling stock largely should relate to the track gauge. as a rule of thumb, narrow gauge modellers often use 3,25 multiplied the gauge for the width of a wagon. So how much weight can you transport in such small buckets keeping the centre of gravity in mind ? I know, peat is probably lighter than clay, sand or gravel...
Have Fun
Juergen