You gotta check if the chainline will work... dunno how disc rears are set up, but it's not hard to modify.
Don't you worry about stresses. A disc rear hub with a fixed cog bolted on is the strongest cog setup ever made by a long way. Waaaay more bomproof than track hubs, cassettes or anything else.
Here is a thread with my bolt-on-cog experiences. Boone makes a $$$ Ti cog and there's another option in that thread somewhere. Or drill/have a machinist drill your own. Cassette BMX cogs work.