Curved fence, straight fence.... The straight fence is more railway-like as when the land was originally purchased they would have taken a 'slice' irrespective of the landowners boundaries unless there were properties to which poked into the yard. The only point the fence would start to curve is by the headshunt as it follows the 'main' line.
Taking Llanfyllin as an example I've highlighted the railway boundary on this OS map extract from NLS. Most of the boundaries are straight unless they follow a natural feature such as the river or accomodate properties sush as Rose Villa below..
While searching for Llanfyllin station to look at the boundaries I came across this postcard on a well known auction site. A pre-grouping photo with a full goods yard - mainly timber. There's also a mixture of wagons, MR, LNWR, L&Y, SECR
Perhaps you could add timber to your goods traffic?
![Llanfyllin Railway Station.jpg Llanfyllin Railway Station.jpg](https://www.westernthunder.co.uk/data/attachments/169/169576-b10b950ec9c71ae1e13468f5b328c7e4.jpg)