These look great, very realistic!
I have used chains in several of my models, and, like you, have been connecting and adjusting them link by link.
Very tedious and time-consuming.
By coincidence I am working on a model that will have a number of chains (complex chains ), and I have been putting that off, hoping the Chain Fairy will visit me while I'm sleeping and use her magic wand to insert them for me.
I've never used SketchyPhysics, figured it was way beyond my tired brain. But after seeing what you did with it I've been checking it out on the off chance that I can grasp enuf of it to maybe get something useful done. Downloaded a bunch of web pages and a couple dozen videos and whatnot.
I'm not very hopeful, but will check them out and see what happens.
Who knows, maybe the Smart Fairy will visit me also