Do you want to go up or down Mastiles Lane?
You could from Gargrave follow Mark House Lane straight from Gargrave > Bell Busk > Airton > Calton > Weets > Mastiles Lane > double back over Malham Moor and Boss Moor, then drop down Moor Lane in the direction of Hetton but turn right half way down and follow the bridleway to Winterburn and spin along the lane back to Hetton.
Reverse my direction if you want to climb up Mastiles Lane. There is very little in the way of mud at the moment, the bridleway your map to is fine at the moment.
Personally, I would prefer the Boss Moor bridleway over the Bordley Hall one, some of it is tarmac.