The plan is to run Accumulo, and on top of it, a geospatial extension called Geomesa (http://www.geomesa.org/).
I am at the "highly experimental" phase. I see that Cloudera has documentation on how to install Accumulo via Cloudera Manager, but then I will have to see how I can add the Geomesa iterator to each worker - I guess I will have to come up with a bootstrap script or something.
Forgot to add. Not a long-running cluster now, but if the experiment succeeds, very likely in the future there will be a long running one.
Installing custom software can be automated via a boostrap script but in this case for Geomesa I think you will need some automation that runs after the cluster is configured via Director, that's true if Geomesa needs the Accumulo service up and running to start. The get Accumulo installed via Cloudera Director you will need to switch from using the UI to using a client configuration file. That allows for more control over your choice of parcel repositories and service types.
You can find configuration files examples here: https://github.com/cloudera/director-scripts/tree/master/configs
Thanks for the advice and for the link.
Geomesa needs Accumulo to be installed already (because it needs to put some .jar files in its lib and lib/ext folders).
I will very likely need to move to using config files.