I'm not sure that wooden narrow gauge platforms have much historical precedent. Have a look at these 19th century photographs of Tan-Y-Bwlch on the Ffestiniog Railway in North Wales:Click here for image - embedding not permitted
They did not have platforms as such, but a sort of gravel area where passengers could alight. The modern stations have platforms after a fashion, made of concrete or some similar paving material, but these are only raised a few centimetres above the ground:
If we are basing our narrow gauge on Ffestiniog practice, as we are for the vehicles, then it would seem sensible to follow with the platforms, which are very different to standard gauge platforms: indeed, one might say that they are hardly platforms at all, but walkways, as they are not significantly above ground level. There is much to be said for simulating this aspect of things, as the current narrow gauge vehicles look wrong with high platforms next to them.