We ended the day in Drymen, a lovely little village with a great pub for dinner. We stayed at a B&B just outside of town, below the abandoned Buchanan Castle. And the sun came out just in time for us to not hike in clear weather.
The castle is amazing. After the end of WWII, the owners removed the roof and abandoned it in order to not pay taxes on a habitable structure, and it has since been swallowed by thick Scottish fauna. It's like a jungle in there. Dark, mossy, impossible to see more than a few yards into the brush. Definitely must be haunted.
I saw a rhubarb plant with leaves bigger around than hula hoops, stalks wider than my forearms, and taller than me. I should have taken a picture.