WooooOOOOOOooooW! This is GREAT!
I wasn't able to see how to even get through, for a looong time. Today I finally saw an option and started to develop the idea. Not very far from that point I got to 4 off and then to 2 off, but still had a bit of trouble, getting to 221, which is the current solution.
A wonderful level! I hope you decide to make some more, some time. :)