Dirt substrate, or monthly replacement of root tabs. Declor any water you put in the tank, no direct sunlight. (algae)
The setup is less than ideal. But they can survive. It will be a fish deathtrap, so if you don't intend to put fish into it, I say give it a try!
I had crypts survive in a non-filtered, no-light, no-heater (with dirt substrate) environment for several years. Growth was extremely slow. Water was stinky (somewhat) And without a light, wasn't something that I noticed much.