Hi Alex,
For rtr, how about this current Bachmann offering?
http://www.mremag.com/news/article/Bachmann-writhlington-collieries-5-plank-wagon-37-065/16428
and http://www.anticsonline.co.uk/593_1_106176200.html
You can see a couple of these wagons (or very similar at least) in the background in a photo in Robin Athill's The Somerset and Dorset Railway (plates between p84 & 5 in my edition).
Paul