There are some trails through Calderglen. One of our routes is to run down the Expressway towards Hamilton and turn into the glen on the right, just before High Blantyre turn-off. Can exit in St Leonards or continue to Newhousemill Road and on through to Torrance House/Strathaven Road.
I have run the glen in pitch dark on two occasions but I was always following, never leading. I wouldn't advise it. V dark, muddy, branches, roots, boulders, etc. and it's a long drop down to the river!
There are some great farm roads (unlit) around there too... across the Strathaven Road round Langlands, Auldhouse and Strathaven.
If no-one else pops up with a suggestion try contacting the
Calderglen Harriers