I know that area very well, I have had some great trips there over the years it’s a lovely area with some beautiful waterfalls on the streams, the Gwesyn valley is a nice walk to Drygarn Fawr and those beehives cairns are great. You mention some marshes and rough walking and guess you are referring to and tried to avoid Bryn Rhudd bog by descending west of it, I know what you mean, south of Drygarn between the head of the Gwesyn to Carnau the whole area is a bog, the first time I ever went there I was standing at the cairn at Carnau and could see the cairns of Drygarn so decided to walk in a direct line to them crossing the heads of the Gewyn and Melyn streams which was a big mistake, it is indeed very rough and is better to contour round. Thanks for sharing its brought back many memories, the Abergwesyn to Tregaron road along the River Irfon valley via the ‘Devils Staircase’ is fantastic and Llyn Brianne reservoir down the road is just stunning and my favourite one in Wales. Nice to see your young lad enjoying himself too.
ATB.