Sorry for the lack of progress on this one. Real life has got in the way so my bench time is almost non-existant.
Just a small update of where things stand at the moment.
I've added the dried mud to the tracks using Acrylic Resin and fine sand/dirt.
Colour was added using Vallejo Acrylics. I've also manage to get a bit more done on the base to add a little more interest.