An internal closed loop misting system with a submersible pump would definitely be an asset for an emersed set-up. Are you planning to have a continuous mist, or having a mist at intervals? DIY or plug & play?
Unfortunately, I am no help with your question... not aware of any plug & play (internal CL misting systems) out there for small footprint set-ups. As you mentioned, most of the good misting systems available have an external reservoir.
Finding a pump for your project may be a challenge. GPH vs. PSI ~ most small circulation pumps just don't have the pressure to make misting nozzles perform properly. I'm not sure (and could be wrong), but seem to recall that a pressure of around 30psi would be enough to run maybe 2 nozzles?
An interesting idea, indeed. Please let us know if your idea bears fruit.